gb - t228 - 2002 tensile testing of metallic materials
DESCRIPTION
A good standard in line with ISO for the tensile testing of metallic materialsTRANSCRIPT
ICS 77.040.10H22
The National Standard of People’s Republic of ChinaGB/T 228-2002
eqv ISO 6892:1998
Metallic materials—Tensile testing at ambient
temperature
Issued on 03-10-2002 Implemented on 01-07-2002Issued by State Quality Supervision and Inspection & Quarantine Bureau of P.R.C
1
GB/T 228-2002
Contents
Foreword 4
ISO Foreword 5
1. Scope 6
2. Referenced Standards 6
3. Principle 6
4. Definitions 6
5. Symbols and descriptions 10
6. Test pieces 12
7. Determination of original cross-sectional area (So) 13
8. Marking of original gauge length (Lo) 13
9. Precision of test equipments 13
10. Test requirements 14
11. Determinations of percentage elongation after fracture (A) and percentage total elongation at
fracture (At)15
12. Determinations of percentage total elongation at maximum force (Agt) and percentage non-
proportional elongation at maximum force (Ag)15
13. Determination of percentage yield point extension (Ae) 16
14. Determinations of upper yield strength (ReH) and lower yield strength (ReL) 16
15. Determination of proof strength, non-proportional extension (Rp) 17
16. Determination of proof strength, total extension (Rt) 18
17. Verification method of permanent set strength (Rr) 18
18. Determination of tensile strength (Rm) 18
19. Determination of percentage reduction of area (Z) 19
20. Numerical rounding-off of the result of property determination 21
21. The accuracy of the result of property determination 22
22. Test result processing 22
23. Test report
Appendix A (standard appendix): Test piece types used for sheet & strip having 0.1mm-<3mm
thickness23
Appendix B (standard appendix): Test piece types used for plate & flat having >=3mm thickness
and wire rod, bar & section material having >=4mm diameters or thickness25
Appendix C (standard appendix): Test piece types used for wire rod, bar & section material hav-
ing <4mm diameters or thickness28
Appendix D (standard appendix): Test piece type used for tubular material 29
Appendix E (suggestive appendix): Test method for the specified value of percentage elongation
after fracture <5%32
Appendix F (suggestive appendix): Shifting method for testing percentage elongation after frac-
ture32
Appendix G (suggestive appendix): Manual method for testing percentage total elongation at
maximum force of long-shape material (such as wire rod, bar & section material)33
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Appendix H (suggestive appendix): Method of successive approximations for testing proof
strength, non-proportional extension (Rp)34
Appendix I (suggestive appendix): Examples of force-discharging method for testing permanent
set strength (Rr0.2)35
Appendix J (suggestive appendix): Error accumulative method for estimating testing uncertainty
of tensile test36
Appendix K (suggestive appendix): Precision of the tensile test—the test result of laboratory 37
Appendix L (suggestive appendix): Cross reference of new and old standard names of properties
and symbols44
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GB/T 228-2002
Foreword
The standard is equivalent to the international standard ISO 6892:1998 < Metallic materials—Tensile test
at ambient temperature>. The main content of this standard is the same as those of ISO 6892:1998, but
partial technical content of this standard is more detailed and the editing structure is also different. Be-
sides, the requirement of numerical rounding-off of the result of property determination and test result
processing two chapters are supplemented in the standard. Meanwhile, the type of test piece is added, ap-
pendix F (suggestive appendix)—the calculating chart for calculating the original gauge length of rectan-
gular cross-section test piece and the references of appendix L (suggestive appendix) are cancelled, ap-
pendix H (suggestive appendix)—Method of successive approximations for testing proof strength, non-
proportional extension (Rp) and Appendix L (suggestive appendix)—Cross reference of new and old stan-
dard names of properties and symbols are supplemented.
The standard is the re-edition and combination of old standard GB/T 228-1987 <Metallic materials—Ten-
sile testing>, GB/T 3076-1982 < Metallic sheet (strip)—Tensile testing> and GB/T 6397-1986 <Test
piece of metallic tensile test>. In comparison with original standard, the following technical contents are
modified and supplemented:
—Referenced Standards
—Definitions and symbols
—Test pieces
—Test requirements
—Method for determining properties
—Numerical rounding-off of the result of property determination
—Description of the accuracy of the result of property determination
Since the date of implementation of this standard, the old standard GB/T 228-1987 <Metallic materials—
Tensile testing>, GB/T 3076-1982 < Metallic sheet (strip)—Tensile testing> and GB/T 6397-1986 <Test
piece of metallic tensile test> have been replaced.
The Appendix A to D of the standard are standard appendixes.
The Appendix E to L of the standard are suggestive appendixes.
This standard was put forward by the State Metallurgical Industry Bureau.
The State Technical Committee for Standardization of Steel takes the special responsibility of administrat-
ing this standard.
This standard was drafted out by: Iron & Steel Research Institute, Jinan Shijin Group Co. Ltd., Baoshan
Iron & Steel Corporation and Information Standardization Research Institute of Metallurgical Industry.
The standard draftsmen are Liang Xinbang, Li Jiulin, Tao Linying, Li Heping & Gao Zhenying.
The standard was issued for the first time in December of 1963, the first re-edition was in September of
1976 and the second re-edition was in February of 1987.
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GB/T 228-2002
ISO Foreword
ISO (International Standardization Organization) is a universal union consisting of the standardization or-
ganization of each country (ISO member) in the world. Generally, the international standard is drafted out
by of the technical committee of ISO. Each ISO member is entitled to join this committee if it is interested
in the project which has been sanctioned by a technical committee. The international organization (both
governmental as well as non-governmental) having relation with ISO may also join the project. ISO has
very close cooperation with International Electrician Committee (IEC) in aspect of electrotechnical stan-
dardization.
The draft of international standard approved by technical committee is sent to the relative ISO members to
vote and it can be issued officially only after being approved by 75% or above voters out of all.
ISO 6892 is instituted by SC1 Monoaxial Testing Subcommittee of ISO/TC164 Technical Committee of
Metallic Mechanical Testing.
The first edition (ISO 6892:1984) is replaced by the second edition.
The Appendix A to D of the standard are standard appendixes.
The Appendix E to L of the standard are suggestive appendixes.
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The National Standard of People’s Republic of China
GB/T 228-2002eqv ISO 6892:1998
Replacement of GB/T 228-1987
GB/T 3076-1982
GB/T 6397-1986
Metallic materials—Tensile testing at ambient temperature
1. Scope
The standard prescribes the principle, definition, symbol & description, test piece & measurement of its
dimensions, test equipment, test requirement, determination of property, numerical rounding-off of the re-
sult of property determination and test report of Metallic materials—Tensile testing at ambient tempera-
ture.
The standard is applicable for determining the tensile property of metallic materials at ambient tempera-
ture. However, negotiation is required for the tensile test of metallic products having small cross-sectional
dimension, such as metallic foil, super fine wire, capillary tube and so on.
2. The referenced standards
The contents contained by the following standards become the normal contents of this standard through
citation. All editions of the cited standards were valid when this standard was published. And they will
also be re-edited, so, the users who use this standard should try to use the latest editions of the following
standards.
GB/T 2975-1998 Steel & steel products—Sampling location & test piece preparation for mechanical test-
ing (eqv ISO 377:1997)
GB/T Principle of numerical rounding-off
GB/T Calibration of extensometer for monoaxial test (idt ISO 9513:1999)
GB/T Inspection of tension tester (idt ISO 7500-1:1986)
GB/T Conversion of steel elongation—the first section: carbon steel and low-ally steel (eqv ISO 2566-
1:1984)
GB/T Conversion of steel elongation—the second section: austenite steel (eqv ISO 2566-1:1984)
3. Principle
In the test, the test piece is tensioned by tensile force to fracture and the one or more than one mechanical
properties in chapter 4 are tested.
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The test is implemented at ambient temperature (10-35oC) unless there is a special requirement. The test
temperature is implemented at 23+/5oC if there is a strict requirement of temperature.
4. Definitions
The following definitions are used in the standard
4.1 Gauge length
The length of columnar or prismatic part of test piece for measuring elongation
4.1.1 Original gauge length (Lo)
The gauge length of test piece before application of force
4.1.2 Final gauge length
The gauge length of test piece after fracture
4.2 Parallel length
The length of parallel part between two end sides of test piece or two holding points of test piece (the test
piece without two end sides)
4.3 Elongation
The increase of original gauge length (Lo) any time during test period
4.4 Percentage elongation
Percentage of the increase of original gauge length to original gauge length (Lo)
4.4.1 Percentage elongation after fracture (A)
It is percentage of permanent elongation after fracture (Lu-Lo) to original gauge length (Lo) (see figure 1).
For the proportional test piece, the subscript is used for symbol A to describe the applied proportionality
factor if the original gauge length is not 5.65√So1) (So is the original cross-sectional area of parallel
length). For example, A11.3 indicates the percentage elongation after fracture of the original gauge length
(Lo), which is 11.3√So. For non-proportional test piece, the subscript is used for symbol A to describe the
applied original gauge length, which is measured by using millimeter (mm) as unit. For example, A80 mm
indicates the percentage elongation after fracture of the original gauge length (Lo), which is 80mm.
4.4.2 Percentage total elongation at fracture
It is the percentage of total elongation of original gauge length (elastic elongation and plastic elongation)
at fracture to original gauge length (Lo) (see figure 1).
4.4.3 Percentage elongation at maximum force
It is the percentage of elongation of original gauge length at maximum force to original gauge length (Lo)
(see figure 1). It should be distinguished between percentage total elongation at maximum force (Agt) and
percentage non-proportional elongation at maximum force (Ag) (see figure 1).
1) 5.65√So=5√(4So/π)
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Figure 1: definitions of elongation
4.5 Extensometer gauge length (Le)
It is the length of parallel-length part of test piece when extensometer is used to measure the elongation of
test piece. It is recommended that Le>=Lo/2 when it is used to test yield strength and proof strength prop-
erties. It is recommended that Le is equal to or approximately equal to Lo when it is used to test the per-
centage yield point extension and the properties of maximum force or after maximum force.
4.6 Extension
It is the increase of extensometer gauge length (Le) any time during test period.
4.6.1 Percentage permanent extension
It is the percentage of the extension of extensometer gauge length after charge and discharge of stresses
on the test pieces to the extensometer gauge length (Le).
4.6.2 Percentage non-proportional extension
It is the percentage of the non-proportional extension of extensometer gauge length at any described mo-
ment during test period to the extensometer gauge length (Le).
4.6.3 Percentage total extension
It is the percentage of the total extension (elastic extension and plastic extension) of extensometer gauge
length at any time during test period to the extensometer gauge length (Le).
4.6.4 Percentage yield point extension
It is the percentage of the extension of extensometer gauge length from yield starting to homogeneous
work hardening starting to the extensometer gauge length (Le) for the metallic material, which has obvious
yield phenomenon (discontinuous yield).
4.7 Percentage reduction of area
It is the percentage of maximum reduction (So-Su) of cross-sectional area of test piece after fracture to the
original cross sectional area (So).
4.8 Maximum force (Fm)
It is the maximum force endured by the test piece after period of yield. It is the maximum force applied in
the test for the metallic material having no obvious yield (continuous yield).
4.9 Stress
It is the quotient of force divided by the original cross-sectional area (So) of test piece any time during pe-
riod of test.
4.9.1 Tensile strength (Rm)
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Stress
Percentage elongation
It is the stress relative the maximum force (Fm).
4.9.2 Yield strength
It is the point of stress when plastic deformation takes place but force doesn’t increases after the metallic
material appears yielding phenomenon during period of test. The upper yield strength (ReH) and lower
yield strength (ReL) should be distinguished.
4.9.2.1 Upper yield strength (ReH)
It is the highest stress when force decreases for the first time after the test piece yields (see figure 2).
4.9.2.2 Lower yield strength (ReL)
It is the lowest stress in the yielding period if the initial instantaneous effect is not considered (see figure
2).
Figure 2: Upper yield strength (ReH) and Lower yield strength (ReL) on different types of curves
4.9.3 Proof strength, non-proportional extension (Rp)
It is the stress when the percentage non-proportional extension is equal to the proof percentage exten-
someter gauge length (see figure 3). The subscript should be used for the symbol to indicate the proof per-
centage. For example, Rp0.2 indicates the stress when the proof percentage non-proportional extension is
0.2%.
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Stress
StressStress
Stress
Initial instant effect Initial instant effect
Percentage extension
Percentage extension Percentage extension
Percentage extension
Figure 3: Proof strength, non-proportional extension (Rp)
4.9.4 Proof strength, total extension (Rt)
It is the stress when percentage total extension is equal to the proof percentage extensometer gauge length
(see figure 4). The subscript should be used for the symbol to indicate the proof percentage. For example,
Rt0.5 indicates the stress when the proof percentage total extension is 0.5%.
Figure 4: Proof strength, total extension (Rt)
4.9.5 Permanent set strength (Rr)
It is the stress when the percentage permanent extension is equal to the proof percentage extensometer
gauge length after stress is unloaded. For example, Rr0.2 indicates the stress when the percentage perma-
nent extension is 0.2.
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Stress
Percentage extension
Stress
Percentage extension
Figure 5: Permanent set strength (Rr)
5. Symbols and descriptions
The symbols applied in the standard and their descriptions are in table 1.
Table 1: Symbols and descriptions
symbols units descriptions
Test pieces
a mm thickness of rectangular cross-sectional test piece or thickness of tube wall
au mm minimum thickness of reduced section of rectangular cross-sectional test piece after
fracture
b mm width of parallel length of rectangular cross-sectional test piece or longitudinal sec-
tional width of tube or width of flat wire
bu mm maximum thickness of reduced section of rectangular cross-sectional test piece after
fracture
d mm diameter of parallel length of circular sectional test piece or diameter of circular wire
du mm minimum thickness of reduced section of circular cross-sectional test piece after frac-
ture
D mm outer diameter of pipe
Lo mm original gauge length
Lo’ mm the original gauge length of determination of Ag (see appendix G)
Lc mm parallel length
Le mm gauge length of extensometer
Lt mm total length of test piece
r mm radius of transition arc
Lu mm gauge length after fracture
Lu’ mm the gauge length after fracture of determination of Ag (see appendix G)
m g mass
ρ g/cm3 density
So mm2 original cross-sectional area
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Percentage extension
Stress
Su mm2 minimum cross-sectional area after fracture
π -- circumference ratio (pi) (at least 4-digit significant figures)
k -- proportionality factor
Z % Percentage reduction of area: (So-Su)/So x 100
Elongation
ΔLm mm Total extension of maximum force (Fm)
-- mm Elongation after fracture: (Lu-Lo)
A % Percentage elongation after fracture: (Lu-Lo)/Lo x 100
At % Percentage total elongation at fracture
Ae % Percentage yield point extension
Ag % Percentage non-proportional elongation at maximum force (Fm)
Agt % Percentage total elongation at maximum force (Fm)
εp % Proof percentage non-proportional extension
εt % Proof total extension
εr % Percentage permanent set extension
Force
Fm N Maximum force
Yield strength-proof strength-tensile strength
ReH N/mm2 Upper yield strength
ReL N/mm2 Lower yield strength
Rp N/mm2 Proof strength, non-proportional extension
Rt N/mm2 Proof strength, total extension
Rr N/mm2 Permanent set strength
Rm N/mm2 Tensile strength
E N/mm2 Elastic modulus
Note: 1N/mm2=1MPa
6. Test piece
6.1 Shape and dimension
6.1.1 General requirement
Shape and dimension of test pieces are according to the shape and dimension of tested metallic product.
Generally, the test piece is prepared from the test piece workblank, which is cut from the pressed work-
blank or ingot casting of product, followed by machining. However, the product having invariant cross
section (such as wire rod, bar & section material) and cast test piece (cast iron and cast nonferrous alloy)
can be tested directly without machining.
The cross section of the test piece can be a circular, rectangular, polygonal or annular shape or some
shapes in special cases.
The test piece is named proportional test piece if its original gauge length and original cross-sectional area
have the relation of Lo=k√So. Internationally, the proportionality factor (k) is 5.56. The original gauge
length should be not less than 15mm1]. The larger value (the value of 11.3 is preferred to use) or non-pro-
portional test piece can be used if the cross-sectional area of test piece is so small that the proportionality
1Note:1] In international standard, it is “not less than 20mm”. It is changed to “not less than 15mm” so that it can be used for the machined proportional test piece with 3mm diameter.
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factor (k) 5.65 can not satisfy the requirement of this minimum gauge length. The original gauge length
(Lo) of non-proportional test piece is independent of its original cross-sectional area (So).
The dimensional tolerance of test piece should meet the requirement of relative appendix (see 6.2).
6.1.2 The machined test piece
If the dimension of holding end of the test piece is not the same with the parallel length of the test piece,
they are jointed via transition arc (see figure 10, 11 & 12). The transition radius of this transition arc is
probably important, hence, if there is no description of transition radius of this transition arc in the relative
appendix (see 6.2), it is recommended that it should be described in the standard of relative product.
The shape of holding end of test piece should match the clampers of test machine. The axial line of test
piece should be coincident with the line of action of force.
The parallel length (Lc) of test piece or the free length between two holding ends of the test piece with
transition arc should be larger than the original gauge length (Lo).
6.1.3 Non-machined test piece
The length between two holding ends should be sufficient if the test piece is the non-machined product or
one part of test bar (see figure 12 & 14) so that there is a sufficient distance between the mark of original
gauge length and holding end [see appendix A-D (standard appendix)].
The holding end and parallel length should be jointed by transition arc for the cast test piece. The transi-
tion radius of this transition arc is probably important. Hence, it is recommended that it should be de-
scribed in the standard of relative product if there is no description of transition radius of this transition
arc in the relative appendix. The shape of holding end of test piece should match the clampers of test ma-
chine. The parallel length (Lc) of test piece should be larger than the original gauge length (Lo).
6.2 Types of test piece
The main types of test piece are described in appendix A-D (standard appendix) according to shapes of
products (see table 2). The types of other products can also be described in the standard of relative prod-
uct.
Table 2: The main types of test piece
types of product
relative appendix
sheet- plate wire rod --- bar --- section material
0.1mm<=thickness>3mm
thickness >=3mm
--
--
diameter or side length>=4mm
diameter or side length<4mm
A
B
C
tubular material D
6.3 Preparation of test piece
The test piece workblank is cut and test piece is prepared according to the standard of relative product or
GB/t 2975.
7. Determination of original cross-sectional area (So)
The determination method of original cross-sectional area (So) and its accuracy should be in accordance
with the requirement of appendix A-D (standard appendix). It is recommended that the measuring instru-
13
ment or device in table 3 is used to test. The original cross-sectional area of the test piece is calculated ac-
cording to original dimension of the test piece and at least four-digit significant figures are required.
Table 3: The resolving ability of measuring instrument or device2] (mm)
cross-sectional dimension of test piece resolving ability (<=)
0.1-0.5
>0.5-2.0
>2.0-10.0
>10.0
0.001
0.005
0.01
0.05
8. Marking of original gauge length (Lo)
The original gauge length is marked by using small mark, thin lineation or thin ink line. However, the
notch, which may cause earlier fracture, should not be used as marking.
For proportional test piece, the calculated value of original gauge length is rounded off to which is closest
to the multiple of 5mm. The middle value is rounded off to the larger side. The marking of original gauge
length should be accurate to +/- 1%.
If the parallel length (Lc) is much longer than the original gauge length, such as the non-machined test
piece, a series of telescoped original gauge lengths can be marked. Sometimes, the line, which is parallel
to longitudinal axial line of test piece, is lined on the surface of test piece and the original gauge length is
marked on this line.
9. The accuracy of test equipment
The test machine is checked according to GB/T 16825 and the accuracy should be 1 grade or higher.
The accurate grade of extensometer should meet the requirement of GB/T 12160. The extensometer with
accuracy no less than 1 grade is used to test Upper yield strength (ReH), Lower yield strength (ReL), Per-
centage yield point extension, Proof strength, non-proportional extension (Rp), Proof strength, total exten-
sion (Rt), Permanent set strength (Rr) and verification of Permanent set strength (Rr). The extensometer
with accuracy no less than 2nd grade is used to test other properties having larger extension, such as Ten-
sile strength (Rm), Percentage total elongation at maximum force, Percentage non-proportional elongation
at maximum force, Percentage total elongation at fracture and Percentage elongation after fracture.
10. Test requirement
10.1 Test rate
Except there is additional description of product, the test rate is dependent on the characteristics of materi-
als and in accordance with following requirements:
10.1.1 The test rate of determination of yield strength and proof strength
10.1.1.1 Upper yield strength (ReH)
The separating rate of the claimer of test machine should be as constant as possible and in the range of
stress rates described in table 4 in scope of elasticity up to upper yield strength
Table 4: Stress rateselastic modulus of material E/
(N/mm2)
stress rate /(N/mm2)·s-1
minimum maximum
2Note: 2] There is no requirement of this table to be described in the international standard. The requirement added herein is to en-sure the accuracy of determination of original cross-sectional area of test piece to meet the requirement of relative descrip-tion.
14
<150000 2 20
>=150000 6 60
10.1.1.2 Lower yield strength (ReL)
If only lower yield strength is tested, the strain rate should be 0.00025/s-0.0025/s in the yielding period of
parallel length of test piece. The strain rate in parallel length should be as constant as possible. If the strain
rate is not adjustable directly, it is adjusted via adjusting yield, viz., adjusting the stress rate before starting
the test. The test machine is not adjusted again before completion of yield.
In any case, the stress rate in elastic range should not be more than the maximum rate in table 4.
10.1.1.3 Upper yield strength and Lower yield strength ((ReH & ReH)
The Upper yield strength and Lower yield strength are tested in the same test. The test condition of Lower
yield strength should be in accordance with the requirement of point 10.1.1.2.
10.1.1.4 Proof strength, non-proportional extension (Rp), Proof strength, total extension (Rt) and Perma-
nent set strength (Rr)
The stress rate should be in the range of those described in table 4.
The strain rate in plastic range and up to proof strength (Proof strength, non-proportional extension, Proof
strength, total extension and Permanent set strength) should be not more than 0.0025/s.
10.1.1.5 Separating rate of clamper
If the test machine is not able to test or control strain rate until completion of yield, the separating rate of
the claimer of test machine, which is equivalent to the stress rate described in table 4, should be used.
10.1.2 Determination of the test rate of tensile strength (Rm)
10.1.2.1 Plastic range
The strain rate of parallel length should not be more than 0.008/s.
10.1.2.2 Elastic range
If there is no test of yield strength or proof strength, the rate of test machine may reach the maximum rate
in the plastic range.
10.2 Holding method
The clamper with appropriate clamping chuck, such as cuneal clamping chuck, screw clamping chuck and
lantern-ring clamping chuck, should be used.
It should be ensured that the held test piece is under axial tensile force only, especially for testing fragile
materials or the Proof strength, non-proportional extension, Proof strength, total extension and Permanent
set strength.
11. Determinations of percentage elongation after fracture (A) and percentage total elongation at
fracture (At)
11.1 The percentage elongation after fracture is tested according to the description of point 4.4.1.
In order to test percentage elongation after fracture, the broken parts of test piece are jointed together care-
fully so that they are on the same axial line and a special mean may also be used to ensure appropriate
connection with each other. Then, the gauge length of test piece after fracture is measured. It is especially
important for the test piece having a small cross section and that having low percentage elongation.
The measuring instrument or device having resolving ability higher than 0.1mm should be used to mea-
sure the gauge length after fracture (Lu) and the accuracy is up to +/-0.25mm. It is recommended that a
special method is used for testing if the described minimum percentage elongation after fracture is less
than 5% [see appendix E (standard appendix)].
15
In principle, it is effective only if the distance between breakpoint and the closest marking of gauge length
is not less than 1/3 of original gauge length. However, the measurement is effective if the percentage elon-
gation after fracture is more than or equal to (>=) the described value no matter where the breakpoint is.
11.2 The gauge length of extensometer (Le) should be equal to the original gauge length (Lo) of test piece
for the test machine that extensometer can be used to test extension at fracture. There is no need to mark
the original gauge length of test piece. The elastic extension is reduced from total extension in order to ob-
tain percentage elongation after fracture if the total extension at fracture is used to test elongation.
In principle, it is effective if the fracture takes place in the gauge length of extensometer. However, the
measurement is effective if the percentage elongation after fracture is more than or equal to (>=) the de-
scribed value no matter where the breakpoint is.
Note: If there is a fixed gauge to be used to test the percentage elongation after fracture in the standard of the product, the
gauge length of extensometer should be equal to this gauge length.
11.3 The percentage elongation after fracture can be tested on a fixed gauge length according to agree-
ment before test followed by conversion into the percentage elongation after fracture of proportional
gauge length through conversion formula or conversion table (for example, the conversion methods of
GB/T 17600.1 and GB/T 17600.2 can be used).
Note: the percentage elongation after fracture has comparability if and only if the gauge lengths or the gauge lengths of ex-
tensometer, the shapes of cross section and areas are all the same, or the proportionality factors (k) are the same.
11.4 The shifting method of appendix F (suggestive appendix) can be used to test the percentage elonga-
tion after fracture in order to avoid scrap of test piece caused by the fracture taking place in the scope be-
yond description of point 11.1.
11.5 The percentage total elongation after fracture is obtained by dividing the total extension at fracture
described in point 11.2 by the original gauge length of test piece (see figure 1).
12. Determinations of percentage total elongation at maximum force (Agt) and percentage non-pro-
portional elongation at maximum force (Ag)
The total extension at maximum force (ΔLm) is obtained on the Force-Extension Curve Diagram tested by
extensometer. The percentage total elongation at maximum force is calculated according to formula (1):
Agt=(ΔLm/Le) x 100 ------------------------------------------ (1)
The non-proportional extension at maximum force is obtained after the plastic extension is reduced from
the total extension at maximum force (ΔLm). Then, it is divided by the gauge length of extensometer to
obtain percentage non-proportional elongation at maximum force (Ag) (see figure 1).
There is a platform at maximum force for some materials. In this case, the percentage total elongation rel-
ative to the maximum force of the midpoint of platform is used (see figure 1).
The gauge length of extensometer should be mentioned in the test report.
The Force-Extension Curve Diagram is not required if the test is implemented on the test machine with a
data acquisition system of computer. The percentage total elongation and relative non-proportional elon-
gation are tested on the point of maximum force.
Appendix G (suggestive appendix) provides a manual testing method.
13. Determination of percentage yield point extension (Ae)3]
3Note:3] There is no description of this point in the international standard. It is added in order to test according to definition 4.6.4.
16
The percentage yield point extension is determined according to definition 4.6.4 and the Force-Extension
Curve Diagram. It the test, the force-extension curve is drawn until reaching uniform strain hardening pe-
riod. On the diagram of curve, the beeline, which is parallel to the plastic section of line of curve of the
curve, is drawn through the ending point of yielding period. The intercept of this parallel on the extension
axis of the diagram of curve is the yield point extension and the percentage yield point extension is ob-
tained by dividing the yield point extension by the gauge length of extensometer (see figure 6).
The percentage yield point extension can be tested by using automatic device (such as PC) or automatic
testing system. The Force-Extension Curve Diagram is not required in this case.
The gauge length of extensometer should be mentioned in the test report.
Figure 6: The percentage yield point extension (Ae)
14. Determinations of upper yield strength (ReH) and lower yield strength (ReL)4]
14.1 For the metallic materials having obvious yield phenomenon (non-continuous yield), the upper yield
strength or lower yield strength or both should be described in the standard of its relative product. The up-
per yield strength and lower yield strength or lower yield strength [in case of figure 2d] should be deter-
mined. The upper yield strength and lower yield strength are determined according to definition 4.9.2.1 &
4.9.2.2 as well as following methods.
14.1.1 Graphical method: the force-extension curve or force-displacement curve is drawn in the test.
Then, the maximum force before the decrease of force for the first time and the minimum force in the
yielding period if the original instantaneous effect is not considered or the constant force of platform are
read and noted down on above curves. And then, they are divided by the original cross-sectional area (So)
of test piece to obtain upper yield strength and lower yield strength (see figure 2). Arbitration test is im-
plemented by graphical method.
14.1.2 Pointer method: in the test, the maximum force indicated by the pointer of dynamometer before it
returns for the first time and the minimum force indicated by the pointer in the yielding period if the origi-
nal instantaneous effect is not considered or the constant force indicated by the pointer when it stops rotat-
ing for the first time are read and noted down on the dynamometer. And then, they are divided by the orig-
inal cross-sectional area (So) of test piece to obtain upper yield strength and lower yield strength.
14.1.3 The upper yield strength and lower yield strength can be tested by using automatic device (such as
PC) or automatic testing system. The Tensile Curve Diagram is not required in this case.
4Note:4] There is no description of this point in the international standard. It is added in order to test according to definition 4.9.2.1 & 4.9.2.2.
17
Stress
Percentage extension
15. Determination of proof strength, non-proportional extension (Rp)
15.1 The proof strength, non-proportional extension is determined according to Force-Extension Curve
Diagram. On the diagram of curve, the beeline, which is parallel to the plastic segment of the curve, and
with distance to this segment on the extension axis equivalent to the proof non-proportional extension
(such as 0.2%) is drawn. The intersection point of this parallel line and the curve shows the force relative
to the proof strength, non-proportional extension. Then, this force is divided by the original cross-sec-
tional area (So) of test piece to obtain the proof strength, non-proportional extension (see figure 3).
It is very important to draw an accurate Force-Extension Curve Diagram.
The following method is recommended to use if the plastic beeline of the Force-Extension Curve can not
be determined definitely so that the parallel line can not be drawn with sufficient accuracy (see figure 7).
In the test, the force is decreased to 10% of that has been reached when the expectant proof strength, non-
proportional extension is exceeded. Then, the force is increased again until it exceeds that has been
reached. In order to test the proof strength, non-proportional extension, a beeline is drawn over hysteresis
loop. Then, the line, which is parallel to this beeline, is drawn by passing through the point, on which the
distance between horizontal axis and the origin of the curve is equivalent to the described percentage non-
proportional extension. The intersection point of this parallel line and the curve shows the force relative to
the proof strength, non-proportional extension. Then, this force is divided by the original cross-sectional
area (So) of test piece to obtain the proof strength, non-proportional extension (see figure 7).
In appendix H (suggestive appendix), the method of successive approximations is provided. It can be used
for testing proof strength, non-proportional extension (Rp).
Note: the origin of the curve can be corrected by various methods. Generally, the following method is used: on the curve,
the line, which is parallel to the line determined by hysteresis loop, is drawn by passing through the elastic rising zone
whose slope is closest to the slope of hysteresis loop. The intersection point between this parallel line and extension axis is
the correctional origin of the curve.
Figure 7: The proof strength, non-proportional extension (Rp) (see 15.1)
15.2 The proof strength, non-proportional extension can be tested by using automatic device (such as PC)
or automatic testing system and the Force-Extension Curve Diagram is not required in this case.
15.3 In practice, the force-clamping chuck displacement curve is drawn to determine the proof strength,
non-proportional extension with proof percentage non-proportional extension >=0.2%. This method is not
used in the arbitration test.
18
Force
Extension
The force relative to Rp
16. Determination of proof strength, total extension (Rt)
16.1 On the force-extension curve, the line which is parallel to the force axis and whose distance to this
axis is equivalent to the proof percentage total extension is drawn. The intersection point of this parallel
line and the curve shows the force relative to the proof strength, total extension. Then, this force is divided
by the original cross-sectional area (So) of test piece to obtain the proof strength, total extension (see fig-
ure 4).
16.2 The proof strength, total extension can be tested by using automatic device (such as PC) or automatic
testing system and the Force-Extension Curve Diagram is not required in this case.
17. Verification method of permanent set strength (Rr)
The force relative to permanent set strength is applied on the test piece and maintained for 10s-12s. The
percentage permanent extension is verified (whether) it does not exceed the described percentage after the
force is discharged (see figure 5).
The method provided in appendix I (suggestive appendix) is used to test the permanent set strength if it is
required in the standard of relative product.
18. Determination of tensile strength (Rm)5]
Tensile strength is tested by Graphical method or pointer method according to definition 4.9.1.
The maximum force after yielding period is read on the force-extension or force-displacement curve or
the dynamometer for the metallic materials having obvious yielding phenomenon (non-continuous yield)
(see figure 8). For the metallic materials having no obvious yielding phenomenon (continuous yield), the
maximum force in the testing period is read on the force-extension or force-displacement curve or the dy-
namometer. The tensile strength is obtained by dividing the maximum force by the original cross-sec-
tional area (So) of test piece.
The tensile strength can be tested by using automatic device (such as PC) or automatic testing system. The
Force-Extension Curve Diagram is not required in this case.
Figure 8: Maximum force (Fm)
19. Determination of percentage reduction of area (Z)
19.1 The percentage reduction of area is tested according to definition 4.7. After fracture, the measure-
ment of minimum cross-sectional area should be accurate to +/12%.
19.2 In the test, the broken parts of test piece are jointed together carefully so that they are on the same
axial line if it is required. For the test piece having a circular cross section, the diameter is measured in the
5Note:5] There is no description of this point in the international standard. It is added in order to test according to definition 4.9.1.
19
Force
Elongation
orthogonal direction of the smallest section of reduced section and the arithmetical mean is used to calcu-
late the minimum cross-sectional area. For the test piece having a rectangular cross section, the maximum
width and minimum thickness of reduced section are measured (see figure 9) and their product is the min-
imum cross-sectional area after fracture.
The percentage quotient of remainder of the minimum cross-sectional area after fracture (Su) subtracted
from original cross-sectional area (So) divided by the original cross-sectional area, viz., [(original cross-
sectional area (So) – the minimum cross-sectional area after fracture (Su))/original cross-sectional area], is
the percentage reduction of area.
19.3 The percentage reduction of area is not tested for the test piece having complicated cross section or
diameter <3mm, such as sheet & thin strip, full section of tubular material, longitudinal arched pipe and
so on. However, the both parties may negotiate the test method if test is required. The test accuracy of the
minimum cross-sectional area after fracture should meet the requirement of point 19.1.
Figure 9: The maximum width and minimum thickness of the reduced section of test piece having a rec-
tangular cross section
Note: the shape of holding ends of test piece is schematic only.
Figure 10: The machined test piece having a rectangular cross section (see appendix A)
20
Holding end
Note:
1) The surface roughness of the test piece having a rectangular cross section with four-side machining
should not be lower than in the arbitration test.
2) The shape of test piece head is schematic only.
Figure 11: Non-proportional test ample (see appendix B)
Note: The shape of test piece head is schematic only.
Figure 12: The test piece having one part without machining (see appendix C)
21
Holding end
Note: The shape of test piece head is schematic only.
Figure 13: The test piece of longitudinal arched pipe (see appendix D)
Figure 14: The test piece of tubular piece (see appendix D)
20. Numerical rounding-off of the result of property determination6]
The test results of properties should be rounded off according to the requirement of standard of relative
product. The rounding off is according to the requirement of table 5 if there is no requirement in the stan-
dard of relative product. The rounding-off method is according to GB/T 8170.
Table 5: The rounding interval of the test result of properties
properties range rounding-off alternation
ReH, ReL, Rp, Rt, Rm <=200N/mm2
>200N/mm2-1000N/mm2
>1000N/mm2
1N/mm2
5N/mm2
10N/mm2
Ae 0.05%
A, At, Agt, Ag 0.5%
Z 0.5%
21. The accuracy of the result of property determination
6Note:6] In the international standard, only the rounding-off alternation of the test result of percentage elongation after fracture is prescribed. It is 0.5%. The rounding interval requirement is added for the test results of other properties.
22
Holding end
Holding end
The accuracy of the result of property determination is dependent on test parameters. There are two types
of test parameters:
Gauging parameter: such as the accurate grades of test machine and extensometer, measuring accuracy of
dimensions of test piece and so on.
Material and test parameters: such as property of material, preparation and geometrical shape of test
pieces, test rate, test temperature and method of data collection and analysis.
The test accuracy of various properties of tensile test can not be determined exactly at present if there is
no sufficient data of various types of materials.
Appendix J (suggestive appendix) provides the guidance of estimating testing uncertainty relative to Gaug-
ing parameter.
Appendix K (suggestive appendix) provides a group of uncertainties of tensile test for steel, aluminum al-
loy and nickel-based alloy via the test in laboratory.
22. Test result processing7]
22.1 The test result is not effective and the same test with same number of test pieces should be imple-
mented again if any case below takes place:
a) The fracture of test piece is out of gauge length or on the making of gauge length marked mechanically
and the percentage elongation after fracture is less than the described minimum value.
b) The test machine has fault in test period and hence the test result is affected.
22.2 If there are two or more than two reduced sections or visible metallurgical defects (such as stratifica-
tion, air bubble, slag inclusion and shrinkage cavity) on the test piece after test, they should be mentioned
in test record and test report.
23. Test report
Generally, test report includes following content:
a) Domestic standard serial number;
b) Identification of test piece;
c) Name & designation of test pieces;
d) Type of test piece;
e) Sampling method and location of test pieces;
f) Result of the tested property
Appendix A(Standard appendix)
Test piece types used for sheet & strip having 0.1mm-<3mm thickness
A1: Shape of the test piece
The holding end of test piece should be broader than the parallel length. There should be a transition arc
between the holding end of test piece and parallel length (Lc) to joint them and the transition radius of
transition arc is at least 20mm (see figure 10). The width of holding end is at least 20mm, but not more
than 40mm.
7Note: 7] There is no description of this point in the international standard. It is added because these matters may take place in prac-tice.
23
According to agreement, the test piece without holding end can also be used, but the free length between
two ends should be Lo+3b for this type of test piece. For the product having width <=20mm, the width of
test piece can be equal to the width of product.
A2: Dimension of test piece
The parallel length should not be less than Lo+b/2. Unless the size of test piece is insufficient, the parallel
length is Lo+2b for arbitration test.
For the test piece having width <=20mm and without holding end, the original gauge length (Lo) should
be 50mm unless there is a special description in the standard of product.
The dimensions of proportional test piece and non-proportional test piece are described in table A1 & ta-
ble A2.
Table A1: The proportional test piece having a rectangular cross section8]
b/mm r/mm
k=5.65 k=11.3
Lo/mm
Lc/mmSr.No. of
test pieceLo/mm
Lc/mmSr.No. of
test piecewith hold-
ing end
without
holding end
with hold-
ing end
without
holding end
10
>=205.65√So
>=15
>=Lo+b/2
arbitration
test:
Lo+2b
Lo +3b
P1
11.3√So
>=15
>=Lo+b/2
arbitration
test:
Lo+2b
Lo +3b
P01
12.5 P2 P02
15 P3 P03
20 P4 P04
Note:
1. The proportional test piece with proportionality factor k=5.65 is preferred to be used. It is recommended that the non-
proportional test piece in table A2 is used if the proportional gauge length is less than 15mm.
2. The parallel length of the test piece with thickness <0.5mm may has small dummy clubs so that the extensometer can
be installed easily if it is required. The distance between the width central lines of upper and lower dummy clubs is origi-
nal gauge length.
Table A2: The non-proportional test piece having a rectangular cross section
b/mm r/mm Lo/mm
Lc/mmSr.No. of test
piecewith holding endwithout holding
end
12.5>=20
50 75 87.5 P5
20 80 120 140 P6
Note: The parallel length of the test piece with thickness <0.5mm may has small dummy clubs so that the extensometer can
be installed easily if it is required. The distance between the width central lines of upper and lower dummy clubs is original
gauge length.
A3: Preparation of test piece
The preparation of test piece should not affect its mechanical property. The work-hardening part of the
test piece caused by shearing or pressing is removed via machining process.
For very thin material, it is recommended to cut it into sheets with the same width. Then, the sheets are
overlapped and oil paper is kept among sheets in order to isolate them and two pieces of sheets are sued to
8Note: 8] There is description of these test pieces. The test pieces added in tables are common test pieces in the standard of product.
24
clamp two sides of the bundle of sheets. The whole bundle of sheets is machined to the dimension of test
piece.
The dimensional tolerance and form tolerance of the machined test pieces should meet the requirement of
table A3. The following are some examples of these tolerances:
a) Dimensional tolerance:
In table A3, for example, if the nominal width of test piece is 12.5mm and dimensional tolerance is +/-
0.2mm, the width of test piece should not be beyond the range of following two values:
12.5mm+0.2mm=12.7mm & 12.5mm-0.2mm=12.3mm
b) Form tolerance:
In table A3, for example, for the test piece with 12.5mm width, which satisfies above machined condition,
the difference between the measured maximum width and minimum width along parallel length (Lc)
should not be more than 0.04mm (in case of arbitration test). Hence, if the minimum width of test piece is
12.40mm, the maximum width of test piece should not be more than following value:
12.4mm+0.04mm=12.44mm
Table A3: The tolerances of width of test piece9]
nominal widths of test
piecedimensional tolerances
form tolerances
common test arbitration test
10
+/-0.2 0.1 0.0412.5
15
20 +/-0.5 0.2 0.05
A4: Determination of original cross-sectional area (So)
The accuracy of determination of original cross-sectional area is up to +/-2%. The error of width should
not be more than +/-0.2% if the error is mainly caused by the measurement of thickness of test piece. The
width and thickness are measured in two sides and middle of gauge length of test pieces. The smallest
cross-sectional area of above three points is used. It is calculated according to equation (A1):
So=ab ----------------------------------------------------- (A1)
Appendix B
(Standard appendix)
Test piece types used for plate & flat having >=3mm thickness and wire rod, bar & section material hav-
ing >=4mm diameters or thickness
9Note:9] In the international standard, the form tolerance is accurate to three digits after radix point. (In this standard), these toler-ances are not required as accurate as international standard. They are accurate to two digits after radix point. The dimen-sional tolerance is different from the description of international standard (in case of calculation of So by using measured di-mensions). The tolerance described in the international standard is +/-1mm. It is too large.
25
B1: Generally, the test piece is machined. The transition arc is used to joint the parallel length and holding
end and the shape holding end of test piece should match the clamping chuck of clamper of test machine
for convenience of holding (see figure 11). The radius of the transition arc between holding end and paral-
lel length (Lc) is as follows:
Circular cross-sectional test piece: >=0.75d;
Rectangular cross-sectional test piece: >=12mm.
The original cross section of test piece can be a circular shape, rectangular shape, foursquare shape or
other special shapes. For rectangular cross-sectional test piece, it is recommended that the ratio of its
width to thickness is 8:1. For the machined circular cross-sectional test piece, the diameter of its parallel
length is not less than 3mm normally10].
The test piece without machining can be used to test for wire rod, bar & section material if it is described
in the standard of relative product.
B2: Dimension of test piece
The parallel length of machined test piece
For circular cross-sectional test piece: Lc>= Lo+b/2. Arbitration test: Lo+2b, unless the size of test piece is
insufficient.
For rectangular cross-sectional test piece: Lc>= Lo+1.5√So. Arbitration test: Lc= Lo+2√So., unless the size
of test piece is insufficient.
B2.2 The parallel length of non-machined test piece
The free length between two clamping chunks of test machine should be sufficient so that the distance be-
tween the marking of original gauge length of test piece and its closest holding end is not less than 1.5d or
1.5b.
B2.3 Original gauge length
B2.3.1 Proportional test piece
The relation between original gauge length (Lo) and original cross-sectional area (So) is as follows for pro-
portional test piece:
Lo=k√So ------------------------------------------------------- (B1)
Therein, the proportionality factor k is 5.65. However, the proportionality factor described in Point 11.3
can be used if it is required in the standard in the relative product.
The dimensions of Circular cross-sectional proportional test piece and Rectangular cross-sectional propor-
tional test piece are in table B1 & table B2 respectively. Other dimensions of proportional test piece can
be described in the standard of relative product.
Table B1: Circular cross-sectional proportional test piece11]
d/mm r/mm k=5.65 k=11.3
Lo/mm Lc/mm Sr.No. of
test piece
Lo/mm Lc/mm Sr.No. of
test piece
25 >=0.75d 5d >=Lo+b/2 R1 10d >=Lo+b/2 R01
1Note: 10] In the international standard, it is “no less than 4mm”. In this standard, it is changed to “no less than 3mm” so that the machined test piece with 3mm diameter can be used.11] In the international standard, only the test piece having 20mm, 10mm & 5mm diameters (R2, R4 & R8 test pieces) are described. In the table, circular cross-sectional test pieces, which are normally described in the standard of product, are added.
26
arbitration
test: Lo+2b
arbitration
test: Lo+2b
20 R2 R02
15 R3 R03
10 R4 R04
8 R5 R05
6 R6 R06
5 R7 R07
3 R8 R08
Note:
1. R2, R4 or R7 test piece is preferred to use if there is no standard of relative product;
2. Total length of test piece depends on the holding method. In principle, Lt>Lc+4d.
Table B2: Rectangular cross-sectional proportional test piece12]
d/mm r/mm
k=5.65 k=11.3
Lo/mm Lc/mmSr.No. of
test pieceLo/mm Lc/mm
Sr.No. of
test piece
12.5
>=12 5.65√So
Lc>=
Lo+1.5√So
Arbitration
test: Lc=
Lo+2√So
R7
11.3√So
Lc>=
Lo+1.5√So
Arbitration
test: Lc=
Lo+2√So
R07
15 R8 R08
20 R9 R09
25 R10 R10
30 R11 R11
Note:
1. The proportional test piece with proportionality factor k=5.65 is preferred to use if there is no standard of rel-
ative product.
B 2.3.2 Non-proportional test piece
There is no stationary relation between original gauge length (Lo) and original cross-sectional area (So).
The dimensions of Rectangular cross-sectional non-proportional test piece are in table B3. Other dimen-
sions of non-proportional test piece can also be used if they are described in the standard of relative prod-
uct.
B2.4 According to agreement, the product with thickness >25mm can be machined to Circular cross-sec-
tional proportional test piece or thinned to Rectangular cross-sectional proportional test piece if there is no
detailed type of test piece described in the standard of relative product and the ability of test machine is
not sufficient.
Table B3: Rectangular cross-sectional non-proportional test piece13]
b/mm r/mm Lo/mm Lc/mm Sr.No. of test piece
12.5 >=12 50 Lc>= Lo+1.5√So
Arbitration test:
Lc= Lo+2√So
P12
20 80 P13
25 50 P14
1Note:12] There is no description of these test pieces in the international standard. In the table, rectangular cross-sectional propor-tional test pieces, which are normally described in the standard of product, are added.1Note:13] There is no description of these test pieces in the international standard. In the table, rectangular cross-sectional non-pro-portional test pieces, which are normally described in the standard of product, are added.
27
38 50 P15
40 200 P16
B3: Preparation of test piece
The horizontal dimensional tolerance of machined test piece should meet the requirement of table B4. The
following are some examples of these tolerances:
a) Dimensional tolerance:
In table B4, for example, if the nominal diameter of test piece is 10mm and dimensional tolerance is +/-
0.07mm, the diameter of test piece should not be beyond the range of following two values:
10mm+0.07mm=10.07mm & 10mm-0.07mm=9.93mm
b) Form tolerance:
In table B4, for example, for the test piece with 10mm diameter, which satisfies above machined condi-
tion, the difference between the measure maximum diameter and minimum diameter along parallel length
(Lc)should not be more than 0.04mm (in case of arbitration test). Hence, if the minimum diameter of test
piece is 9.99mm, the maximum diameter of test piece should not be more than following value:
9.99mm+0.04mm=10.03mm
B4: The transversal dimensional tolerance14]
namesnominal transversal di-
mensiondimensional tolerance form tolerance
machined circular-sectional di-
ameter
3 +/-0.05 0.02
>3-6 +/-0.06 0.03
>6-10 +/-0.07 0.04
>10-18 +/-0.09 0.04
>18-30 +/-0.10 0.05
transversal dimensions of rectan-
gular cross-sectional test piece
with four-side machining
equivalent to the tolerance of diameter of circular cross-sectional test
piece
transversal dimensions of rectan-
gular cross-sectional test piece
with opposite two-side machin-
ing
3+/-0.01 0.05
>3-6
>6-10+/-0.02 0.1
>10-18
>18-30+/-0.05 0.2
>30-50
B4: Determination of original cross-sectional area (So)
The original cross-sectional area is calculated according to dimensions of tested original test piece and the
accuracy of each measured determination is up to +/-0.5%.
14] In the international standard, the accuracies of dimensional & form tolerances of circular cross-sectional test piece is ac -curate to three digits after radix point. In the standard, these tolerances are not required as accurate as international standard. They are accurate to two digits after radix point only. For the rectangular cross-sectional test piece with opposite two-side machining, there is no description of tolerance, but the dimensional tolerance is added in the standard. The form tolerance is different from that of international standard. It is too large in the international standard.
28
For circular cross-sectional test piece, the diameter is measured on two ends and middle of gauge length in
the orthogonal directions and the arithmetical mean is used. The smallest cross-sectional area of three lo-
cations is used (as original cross-sectional area) and the calculation is as follows:
So=1/4πd2----------------------------------------------------- (B2)
For rectangular cross-sectional test piece, the width and thickness are measured on two ends and middle
of gauge length and the smallest cross-sectional area of three locations is used. The calculation is accord -
ing to equation (A1).
For the constant cross-sectional test piece, the original cross-sectional area can be calculated according to
the measured length, mass and density of test pieces. The accuracy of length of test piece is up to +/-0.5%,
accuracy of mass of test piece is up to +/-0.5% and at least three significant digits are used for density.
The calculation of original cross-sectional area is as follows:
So=(m/ρLt)x1000------------------------------------------------ (B3)
Appendix C (Standard appendix)
Test piece types used for wire rod, bar & section material having <4mm diameters or thickness
C1: Shape of test piece
The test piece is one part of product generally. It is not machined (see figure 12).
C2 Dimension of test piece
The original gauge lengths are 200mm and 100mm. Except the free length between two holding ends for
the wire rod having a small diameter may be Lo, for other cases, the free length of two clamping chucks of
test machine should be at least Lo+50mm. See table C1.
The minimum free length between two holding ends can be 50mm if the percentage elongation after frac-
ture is not tested.
Table C1: Non-proportional test piece
d or a/mm Lo/mm Lc/mm Sr.No. of test piece
<=4 100 >=150 R9
200 >=250 R10
C3: Preparation of test piece
It should be straightened sufficiently if the product is delivered by coiled state.
C4: Determination of original cross-sectional area (So)
Determination of original cross-sectional area should be accurate to +/-1%. The minimum cross-sectional
area is measured on two ends and middle of gauge length and the smallest cross-sectional area of three lo -
cations is used.
29
For circular cross-sectional product, the diameter is measured in the orthogonal directions and the arith-
metical mean is used to calculate the cross-sectional area. The calculation is according to equation (B2).
For rectangular cross-sectional and quadrate products, the width and thickness are measured and the cal-
culation is according to equation (A1).
The original cross-sectional area can be calculated according to the measured length, mass and density of
test pieces. The calculation is according to equation (B3).
Appendix D(Standard appendix)
Test piece type used for tubular material
D1: Shape of test piece
The test piece can be full-wall (solid) longitudinal arched test piece (see figure 13) & tubular test piece
(see figure 14), full-wall transverse test piece or circular cross-sectional test piece machined by using tube
thickness.
According to agreement, the longitudinal arched test piece and transverse test piece without holding ends
can be used. But the test piece with holding ends is used in arbitration test.
D2: Dimension of test piece
D2.1 Longitudinal arched test piece
The dimensions described in table D1 are used for the longitudinal arched test piece. Generally, the longi-
tudinal arched test piece is suitable for the tubular material having tube wall>0.5mm.
Two end of longitudinal arched test piece can be pressed to flat so that it can be clamped by test machine
easily. But the parallel length (Lo) should not be pressed.
For the test piece without two holding ends, the free length between two clamping chunks of test machine
should be sufficient so that the distance between the marking of original gauge length of test piece and its
closest holding end is not less than 1.5b.
Table D1: longitudinal arched test piece15]
D/mm b/mm a/mm r/mm
k=5.65 k=11.3
Lo/mm Lc/mmSr.No. of
test pieceLo/mm Lc/mm
Sr.No. of
test piece
30-50 10
original
tube wall
thickness
5.65√SoLc>=
Lo+1.5√So
Arbitration
test: Lc=
Lo+2√So
S1
11.3√So
Lc>=
Lo+1.5√So
Arbitration
test: Lc=
Lo+2√So
S01
>50-70 15 S2 S02
>70 20 S3 S03
<=100 19
50
S4
>100-200 25 S5
>200 38 S6
Note: The proportional test piece with proportionality factor k=5.65 is preferred to be used.
D2.2 Tubular test piece
The dimensions of tubular test piece are described in table d2.
1Note: 15] There is no special description of these test pieces in the international standard. In the table, these longitudinal arched test pieces are normally described in the standard of product.
30
There should be two plugs on two sides of the tubular test piece and the distance between the plug to the
closest marking of gauge length is not less than D/4(see figure D1). The distance is D in arbitration test if
the length of material is sufficient. The extended distance of plug beyond clamping chuck of test machine
in the direction of gauge length is not more than D and its shape should not interfere the distortion in
gauge length.
Two holding ends of tubular test piece can be pressed to flat (see figure D2) and the test can be imple-
mented with flat plug in two holding ends of test piece or without flat plug. However, the tubular test
piece is not pressed in arbitration test and the plug is used.
Table D2: Tubular test piece16]
Lo/mm Lc/mm Sr.No. of test piece
5.65√So Lc>= Lo+D/2, Arbitration test:
Lc= Lo+2D
S7
50 >=100 S8
Figure D1: Location of plug of tubular test piece
Figure D2: The tubular test piece with pressed two holding ends
D2.3 Machined transverse test piece
For machined transverse rectangular test piece, the dimensions described table A1 or table A2 of appendix
A (standard appendix) are used if the thickness of tube wall is less than 3mm and the dimensions de-
scribed table B2 or table B3 of appendix B (standard appendix) are used if the thickness of tube wall is
more than or equal to 3mm.
The dimensions of transverse rectangular test piece different from those described in appendix A (stan-
dard appendix) and appendix B (standard appendix) in the standard of relative product.
1Note:16] There is no description of these test pieces in the international standard. The tubular test piece is added.
31
Holding end
For the test piece without two holding ends, the free length between two clamping chunks of test machine
should be sufficient so that the distance between the marking of original gauge length of test piece and its
closest holding end is not less than 1.5b.
The transverse test piece should be strengthened by using some particular means.
D2.4 Machined longitudinal circular cross-sectional test piece of tubular-wall thickness (solid)
The dimensions of test piece described in table B1 of appendix B (standard appendix) are used for the ma-
chined longitudinal circular cross-sectional test piece. The dimension of machined circular cross-sectional
test piece should be described in the standard of relative product according to thickness of tube wall. The
dimensions in table D3 are used if there is no detailed description.
Table D3: Machined longitudinal circular cross-sectional test piece of tubular-wall thickness (solid)17]
Thickness of tube wall/mm test piece applied
8-13 R7
>13-16 R5
>16 R4
D3: Determination of original cross-sectional area (So)
Determination of original cross-sectional area should be accurate to +/-1%.
For longitudinal arched test piece of circular pipe, the width and tube-wall thickness are measured on two
ends and middle of gauge length and the smallest cross-sectional area of three locations is used. The cal-
culation is according to equation (D1). The nominal value is used for outer diameter in calculation.
So=(b/4)(D2-b2)1/2 + (D2/4) arcsin (b/D) –(b/4)[(D-2a)2-b2]1/2 – [(D-2a)/2]2arcsin[b/(D-2a)] ------------ (D1)
The following simplified formula can be used to calculate the original cross-sectional area of longitudinal
arched test piece of circular pipe:
When (b/D)<0.25, So=ab[1+b2(6D(D-2a))] -------------------------------------------- (D2)
When (b/D)<0.17, So=ab -------------------------------------------- (D3)
For transverse rectangular cross-sectional test piece of circular pipe, the width and thickness are measured
on two ends and middle of gauge length and the smallest cross-sectional area of three locations is used.
The calculation is according to equation (A1).
For tubular test piece, outer diameter and the tube-wall thicknesses of four sites are measured on its one
end in orthogonal direction and the arithmetical mean is used. The calculation is according to equation
(D4):
So=πa(D-a) -------------------------------------------------- (D4)
For the tubular test piece and the longitudinal or transverse cross-sectional test piece without holding
ends, the original cross-sectional area can be calculated according to the measured length, mass and den-
sity of test pieces. The calculation is according to equation (B3).
17] There is no special description of these test pieces in the international standard. In this standard, the description of ma-chined longitudinal circular cross-sectional test piece of tubular-wall thickness (solid) is added.
32
Appendix E(Suggestive appendix)
Test method for the specified value of percentage elongation after fracture <5%
The recommended method is as follows:
Before test, a small marking is marked on one end of parallel length. Then, the divider, which is adjusted
to gauge length, is used to draw a arc by using this marking as centre of circle. After it is tensed to frac-
ture, the broken test piece is kept on a device and screw is used to force it axially so that the broken pieces
may joint together tightly. And then, the second arc is drawn by using the original centre of circle as cen-
tre of circle and original radius as radius. The distance between the two arcs are measured by using tool
microscope or other appropriate equipment to obtain the elongation after fracture. It is accurate to +/-
0.02mm. The surface of test piece may be painted before test so that the drown arc is clear.
The extensometer method described in point 11.2 can be used as another method for testing.
Appendix F(Suggestive appendix)
Shifting method for testing percentage elongation after fracture
The following can be used to test the percentage elongation after fracture in order to avoid scrap of test
piece caused by the fracture taking place in the scope beyond description of point 11.1:
a) The original gauge length (Lo) is divided into N equal parts before test.
b) After test, symbol X is used to indicate the gauge length marking of short part after fracture and Y is
used to indicate the equal-part marking of long part of test piece at fracture. The distance between this
marking and fracture point is the closest to the distance between fracture point and the gauge length mark-
ing X.
If the number of equal parts between X and Y is n, the calculation of percentage elongation after fracture
is as follows:
1) If N-n is an even [see figure F1a)], the distance between X and Y is measured and the distance between
Y to marking Z, from which there are (N-n)/2 equal parts to marking Y. The percentage elongation after
fracture is as following equation (F1):
A=(XY + 2YZ - Lo)/Lo x 100% ---------------------------------- (F1)
2) If N-n is an odd number [see figure F1b)], the distance between X and Y is measured and the distance
between Y to marking Z’ & Z”, from which there are (N-n-1)/2 & (N-n+1)/2 equal parts to marking Y.
The percentage elongation after fracture is as following equation (F2):
A=(XY + 2YZ’ + YZ” - Lo)/Lo x 100% ---------------------------------- (F2)
33
Note: the shape of holding ends of test piece is schematic only.
Figure F1: The schematic diagram of shifting method
Appendix G(Suggestive appendix)
Manual method for testing percentage total elongation at maximum force of long-shape material (such as
wire rod, bar & section material)
The extensometer method described in point 12 can be replaced by following manual methods. However,
the extensometer method should be used in arbitration test.
The method of this appendix is used to measure the non-proportional elongation of longest part of test
piece after tensile test at maximum force and the percentage total elongation is calculated according to this
elongation.
Before test, the equal-part marking is marked on the gauge length and the length of two equal parts is
equal to the divisor of original gauge length (Lo’). The marking of original gauge length (Lo’) is accurate
to +/-0.5mm. This length (Lo’) is the function of percentage total elongation and should be described in
the standard of product. The gauge length after fracture (Lu’) is measure on the longest part of the test
piece after fracture and accurate to +/-0.5mm. The following conditions should be satisfied so that the
measurement is effective.
a) The distance of measurement zone is at least 5d far away from fracture point and 2.5d far away from
clamping chunk (of test machine).
b) The original gauge length for measuring is at least equal to the described value in the standard of prod-
uct.
The calculation of percentage non-proportional elongation at maximum force is according to equation
(G1):
Ag=(Lu’-Lo’)/Lo’ x 100% ---------------------------------- (G1)
34
The calculation of percentage total elongation at maximum force is according to equation (G2):
Agt=Ag + (Rm/E) x 100% ---------------------------------- (G2)
Therein, the elastic modulus (E) is described in the standard of relative product.
Appendix H18]
(Suggestive appendix)
Method of successive approximations for testing proof strength, non-proportional extension (Rp)
H1: The method of successive approximations is applicable for testing the proof strength, non-propor-
tional extension of the metallic material having no obvious elastic straight segment. However, it is also
suitable for testing the proof strength, non-proportional extension of the metallic material having elastic
straight segment with height >=0.5Fm on the Force-Extension Curve Diagram. The method of successive
approximations is also applicable for the automatic testing of tensile test of this property.
H2: Method
The proof strength, non-proportional extension is determined by using Force-Extension Curve Diagram.
In the test, the force-extension curve is drawn until at least exceeding the range of the expected proof
strength, non-proportional extension. On the force-extension curve, a point Ao is randomly taken and set
as the force F0p0.2 when the proof strength, non-proportional extension is 0.2% and B1 & D1 two points on
the curve, which are relative to force 0.1 F0p0.2 and 0.5 F0
p0.2 are also chosen and a beeline (B1D1) is drawn
through these two points. A segment OC (OC=0.2%Le· n, wherein n is amplification of elongation) is in-
tercepted from the origin (it is corrected if it is necessary) (to C on the elongation axis). Then, a beeline
CA1, which is parallel to B1D1, is drawn through point C and intersects curve at A1 point. If point A1 and
Ao are coincident, F0p0.2 is the force when the proof non-proportional extension is 0.2%.
If point A1 and Ao are not coincident, above steps should be repeated again to approximate. Similarly, the
force F1p0.2 of point A1 is taken and B2 & D2 two points on the curve, which are relative to force 0.1 F1
p0.2
and 0.5 F1p0.2 are also chosen and a beeline (B2D2) is drawn through these two points. Then, a beeline CA2,
which is parallel to B2D2, is drawn through point C and intersects curve at A2 point. In such a approach to
approximate gradually until the intersection point An and An-1 are coincident (see figure H). The force of
point An is that the force when the proof non-proportional extension is 0.2%. It is divided by the original
cross-sectional area of test piece to obtain proof strength, non-proportional extension Rp0.2.
The slope of the finally obtained beeline BnDn can be used as reference slope to determine other proof
strength, non-proportional extension normally.
1Note:18] There is no description of this appendix in the international standard. The method of this appendix is applicable for the automatic testing of tensile test.
35
Figure H1: Method of successive approximations for testing proof strength, non-proportional extension
(Rp)
Appendix I19]
(Suggestive appendix)
Examples of force-discharging method for testing permanent set strength (Rr0.2)
Test material: steel, the expected permanent set strength Rt0.2≈800N/mm2.
Test dimensions: d=10.00mm & So=78.54mm2.
Extensometer: watch-like extensometer, 1-gradu accuracy, Le=50mm and each unit scale is 0.01mm.
Test machine: maximum measurement range is 200kN and dial range is 100kN.
Test rate: according to the requirement of point 10.1.1.4.
According to the expected permanent set strength, the pretension corresponding to 10% stress is calcu-
lated as follows:
Fo=Rt0.2 · So x 10%=6283.2N
It is 6000N after rounding. At this moment, the conditional null point of extensometer is 1 unit scale.
The gauge length of extensometer is 50mm. the permanent extension of the tested permanent set strength
Rt0.2 is 50x0.2%=0.1mm. It is converted into unit scale number of extensometer herein, viz., 0.1/0.01=10
(unit scale).
From applying force for the first time from point Fo to the test piece having total extension on the gauge
length of extensometer (corresponding to unit scale number of extensometer): 10+(1-2)=11-12 (unit
scale). Because the conditional null point of extensometer is 1 unit scale, total is 13 unit scales. The force
is maintained for 10-12s and then decreased to Fo. The reading of extensometer is 2.3 unit scales at this
moment, viz., the permanent extension is 1.3 unit scales.
1Note:19] There is no description of this appendix in the international standard. It is added to provide a example of permanent set strength Rt0.2.
36
Force
Elongation
The force is applied for the second time until the reading of extensometer is as follows: 13 unit scales (last
reading) plus 10 unit scales (the proof permanent extension) minus 1.3 unit scales (the obtained permanent
extension) plus 1-2 unit scales, viz., 13+(10-1.3)+2=23.7 unit scales. The force is maintained for 10-12s
and decreased to Fo to obtain 7.3 unit scales of permanent extension.
The force is applied for the second time until the reading of extensometer is as follows: 23.7+(10-
7.3)+1=27.4 unit scales.
The test continues until the reading of permanent extension is equal to or lightly more than 10 unit scales.
The test record is in table I1.
The calculation of permanent set strength Rt0.2 is as follows:
Ft0.2=[(10.5-10)x61000+(10-9.7)x62000]/(10.5-9.7)=61375N
Accordingly:
Rt0.2 =61375/78.54=781.45N/mm2
According to the requirement of table 5, the result after rounding off is as follows:
Table I1: Records of force-permanent extension data
force/N reading of extensometer under
applying force (unit scale)
reading of extensometer under
pretension (unit scale)
permanent extension
(unit scale)
6000
41000
57000
61000
62000
1.0
13.0
23.0
27.4
28.7
--
2.3
8.3
10.7
11.5
--
1.3
7.3
9.7
10.5
Appendix J(Suggestive appendix)
Error accumulative method for estimating testing uncertainty of tensile test
J1: Foreword
The method and essentials of estimating testing uncertainty of tensile test are put forward according to the
error accumulative principle, the requirements of measurement error described by standards of test
method & verification. Because different materials have different responses on different control parame-
ters, such as strain rate or stress rate, it is not possible to obtain uniform testing uncertainty for all materi-
als. The error accumulative method provided herein may be considered as upper limit of uncertainty tested
in laboratory according to the test of this standard (1-grade test machine and 1-grade extensometer).
It is to be noted that the testing uncertainty is considered as the inherent dispersion caused by some inher-
ent factors, such as non-uniformity of material when the total dispersion of test result is evaluated. The
sources of influence on two dispersions can not be separated out through the method of analysis and sta-
tistics of comparative test given in appendix K. Another effective method of estimating the dispersion ob-
tained in laboratory is to use a kind of certified standard material (CRM), which may ensure the property
of material. The selected standard material (CRM) used for tensile testing at ambient temperature is the
37
standard Ni-Cr alloy (Nimonic 75) having 14mm diameter. The weight of each batch of this material is 1t.
It is under certifying procedure of European Community Bureau of Reference (BCR).
J2: Estimation of uncertainty
J2.1 The parameter unrelated to material
There is comparatively sufficient development of error accumulative method, wherein the errors caused
by various sources of error are accumulative together. Recently, the estimation of accuracy and uncer-
tainty is described by two ISO documents (ISO 5725-2 and Guidance of Expression of Testing Uncer-
tainty).
The conventional power & root methods are used in following analysis. In table J1, the expected values of
errors and uncertainties of various test parameters of tensile property are given. In principle, some tensile
properties can be tested by higher accuracy because of the characteristics of stress-strain curve. For exam-
ple, upper yield strength ReH is only dependent on testing errors of force and cross-sectional area and
proof strength is dependent on the testing errors of force, distortion (displacement), gauge length and
cross-sectional area. For percentage reduction of area (Z), the testing errors of cross-sectional area before
and after tests should be considered.
Table J1: Determination of the maximum allowable testing uncertainty of data of tensile test (power & root methods are used)
ParametersErrors of tensile property/%
ReH ReL Rm Rp A Z
Force
Strain1) (displacement)
Gauge length L1)o
So
Su
Expected value of uncertainty
1
--
--
1
--
+/-√2
1
--
--
1
--
+/-√2
1
--
--
1
--
+/-√2
1
1
1
1
--
+/-√4
--
1
1
--
--
+/-√2
--
--
--
1
2
+/-√5
1) Suppose according to verified 1-grade extensometer.
J2.2 The parameter related to material
For tensile testing at ambient temperature, the tensile properties that materials are obviously affected by
strain-rate (or stress-rate) control parameters are ReH, ReL and Rp. tensile strength Rm is also relative to
strain rate. In the test, the strain rate which is much higher than the tested Rp is generally used for testing
so that its sensitivity to the effect of strain rate is less.
In principle, the effect of strain rate on property of material is tested before calculating accumulative error
(see figure J1 & figure J2). The limited data is applicable and following examples can also be used to esti-
mate the testing uncertainty of some materials.
In table J2 & J3, a group of typical data examples, in which the material is affected by the range of strain
rate descried in the standard. Meanwhile, the effect of strain rate on the described strength of several types
of material is given in table J2.
Table J2: Examples of the effect on the proof strength Rp0.2 at ambient temperature in the allowable range
of strain rates described in the standard
materials nominal components Rp0.2 average/(N/
mm2)
effect of strain rate
on Rp0.2/%
equivalent error/%
38
ferrite steel: pipeline
steel & plate steel
(Fe430)
Cr-Mo-V-Fe(rest)
C-Mn-Fe(rest)
680
315
0.1
1.8
+/-0.5
+/-0.9
austenitic steel:
X5CrNiMo17-12-2
17Cr, 11Ni-Fe(rest) 235 6.8 +/-3.4
Ni alloy: NiCr20Ti
NiCrCoTiAl25-20
18Cr, 5Fe, 2Co-Ni(rest)
24Cr, 20Co, 3Ti, 1.5Mo &
1.5Al-Ni(rest)
325
790
2.8
1.9
+/-1.4
+/-0.95
J2.3 Total testing uncertainty
The data unrelated to material described in table J1 and the data of effect of strain rate on the proof
strength described in table J2 are integrated to obtain total estimated testing uncertainty of each type of
material. The result is in table J3.
In order to integrate total uncertainty, half value of the effect on the proof strength at ambient temperature
in the range of strain rates described in the standard is taken and used as equivalent error. For example,
the effect on the proof strength Rp0.2 of X5CrNiMo17-12-2 stainless steel is 6.8% in the allowable range of
strain rate. That means its half is equal to +/-3.4% error. Hence, the total uncertainty of X5CrNiMo17-12-
2 stainless steel is as follows:
+/-√(22+3.42)=+/-√15.6=+/-3.9%
Table J3: Examples of expected values of total testing uncertainty of the proof strength at ambient temper-
ature tested according to this standard
materialsRp0.2 average/(N/
mm2)
values from table
J1/%
values from ta-
ble J2/%
expected values of to-
tal testing
uncertainty /%
ferrite steel: pipeline steel
& plate steel (Fe430)
680
315
+/-2
+/-2
+/-0.05
+/-0.9
+/-2.0
+/-2.2
austenitic steel: X5CrN-
iMo17-12-2
235 +/-2 +/-3.4 +/-3.9
Ni alloy: NiCr20Ti
NiCrCoTiAl25-20
325
790
+/-2
+/-2
+/-1.4
+/-0.95
+/-2.4
+/-2.2
J3: Conclusions
The essentials of estimating testing uncertainty of tensile test at ambient temperature by using the error ac-
cumulative method are put forward and some examples wherein the material affects test parameter. It is
noted that it is probably required to correct the calculated uncertainty in order to contain the weighting
factor, which is in accordance with the Guidance of Expression of Testing Uncertainty. This work is going
to be started after the optimal method is recommend to use by the European Laboratory and ISO divisions
finally. Besides, there are also other factors to affect tensile property, such as test piece bending, method
of holding test piece, control mode of test piece, i.e., the control mode of extensometer or cross head.
They may all affect testing tensile property. However, the effect of other factors can not be included in ac-
cumulative error because there are no sufficient applicable quantitative data to utilize at present. It should
be pointed out that only the estimation of uncertainty caused by testing technology can be given by this er-
39
ror accumulative method. It can not give the allowable tolerance for the inherent dispersivity of test data
caused by non-uniformity of material.
Finally, it should be known that a applicable method should be provided to avoid the total testing uncer-
tainty caused by test machine, including the clamping chunk, which is not approved to be qualified at
present, and bending after the appropriate standard material is available.
Note: ε=plastic strain rate, unit is (mm/mm) · min-1
Figure J1: Change of lower yield strength (ReL) of plate steel along with strain rate (ambient temperature)
Note: ε=plastic strain rate, unit is (mm/mm) · min-1
Figure J2: Change of proof strength Rp0.2 of NiCr20Ti alloy along with strain rate (22oC)
40
Max. expected stress error
Appendix K(Suggestive appendix)
Precision of the tensile test—the test result of laboratory
K1: The reason of uncertainty in tensile test
The accuracy of tensile test is affected by many factors, such as material, test piece, test equipment, test
procedure, calculation method of mechanical property and so on. In detail, the following factors may
cause uncertainty in tensile test
--the non-uniformity of material, which exists in the same batch of the same furnace;
--the geometry, preparation method and tolerance of the test piece;
--the clamping method and axis direction of force application;
--test machine of tensile test and accessorial measurement system (rigidity and methods of drive, control
& operation);
--measurement of dimensions of test piece, marking of gauge length, gauge length of extensometer, mea-
surement of force and elongation;
--the test temperature and loading rate on each stage of test;
--the software error due to human caused mistakes or the software error relative to determination of tensile
property
The effects of above factors can not be examined by the requirement and tolerance of this standard. The
uncertainty, which is close to the result of industrial test condition, can be determined through laboratory
test. However, the error relative material can not be separated from the error caused by test method.
K2: Procedure
The results of laboratory tests (test A, test B & test C) show some typical examples of uncertainty, which
are obtained when the metallic material is tested.
A fixed number of rough test pieces are selected randomly from the materials, which are tested. Then, the
uniformity of selected rough test pieces is checked in order to provide the inherent dispersion (variance??)
of mechanical property of rough test piece itself. And then, the rough test pieces are sent to each labora-
tory to prepare test pieces by machining according to the normal requirement of drawing of each labora-
tory. It is only required that the test piece and test itself should meet the requirement of relative standard.
It is suggested that the same operator uses the same test machine to complete the test as soon as possible.
In table K1, K2 & K3, three types of errors are expressed by the relative uncertainty coefficient:
UCt=(+/-)2Sr√X (%) ------------------------------------ (K1)
UCL=(+/-)2SL√X (%) ------------------------------------ (K2)
UCR=(+/-)2SR√X (%) ------------------------------------ (K3)
Therein, X—total average;
St—estimation value of the repeated standard deviation in laboratory;
SL—estimation value of variation degree of laboratory;
SR—estimation value of accuracy of test method: reproducible standard deviation
41
The values are all in the confidence interval close to 95% of X. It is required to calculate each material
and each property.
K3: Test result of test A (international)
Test materials: Aluminum, steel and alloy;
Number of laboratories for testing: 6;
Number of test pieces of each material in each laboratory: 6;
Test piece: circular cross-sectional test piece with a 12.5mm diameter and 62.5mm gauge length (5-time
diameter test piece);
Test result: the test result is in table K1. The lower yield strength (ReL) and 0.2%proof strength (Rp0.2) are
not differentiated.
K4: Test result of test B (international)
Test materials: steel;
Number of laboratories for testing: 18;
Number of test pieces of each material in each laboratory: 5;
Test piece: (1) The sheet metal with 2.5mm thickness. The test piece has a rectangular cross section and
the width is 20mm & gauge length is 80mm. (2) The bar material has a circular cross section with a 10mm
diameter and the gauge length is 50mm (5-time diameter test piece);
Test result: the test result is in table K2. The lower yield strength (ReL) and 0.2%proof strength (Rp0.2) are
not differentiated.
K5: Test result of test C (domestic)
Test materials: steel and aluminum alloy;
Number of laboratories for testing: 14;
Number of test pieces of each material in each laboratory: 5;
Test piece: (1) The sheet metal with <3mm thickness. The test piece has a rectangular cross section and
the width is 12.5mm & gauge length is 50mm. (2) The sheet metal with >3mm thickness. The test piece
has a rectangular cross section and the width is 20mm & gauge length is 5.65√So. (3) For the coiled bar
material, the non-machined test piece is used and gauge length is 50mm. (4) The bar material has a circu-
lar cross section with a 10mm diameter and the gauge length is 50mm (5-time diameter test piece);
Test result: the test result is in table K3.
Table K1: The result of tensile test in laboratory of Test A (international)
materials aluminum aluminum carbon steel austenitic stain-
less steel
nickel alloy martensite
stainless steel
brand EC-H19 2024-T351 C22 X7CrNiMo17-12-2 NiCr15Fe8 X12Cr13
test piece circular cross
section
circular
cross section
circular cross
section
circular cross
section
circular
cross section
circular cross
section
Rp0.2/(N/mm2)Total Average
UCr / %
UCL/ %
158.4
4.12
0.42
362.9
2.82
0.98
402.4
2.84
4.04
480.1
2.74
7.66
268.3
1.86
3.94
967.5
1.84
2.72
42
UCR/% 4.14 2.98 4.94 8.14 4.36 3.28
Rm/(N/mm2)Total Average
UCr / %
UCL/ %
UCR/%
179.9
4.90
-
4.90
491.3
2.84
1.00
2.66
596.9
1.40
2.40
2.78
694.6
0.78
2.28
2.40
695.9
0.86
1.16
1.44
1.253
0.50
1.16
1.26
A/%Total Average
UCr / %
UCL/ %
UCR/%
14.61
8.14
4.09
9.10
8.04
6.94
17.58
18.90
25.63
6.00
8.18
10.12
35.93
3.93
14.36
14.90
41.58
3.22
7.00
7.12
12.39
7.22
13.70
15.48
Z/%
Total Average
UCr / %
UCL/ %
UCR/%
79.14
4.86
1.46
5.08
30.31
13.80
1924
23.66
65.59
2.56
2.88
2.88
71.49
2.78
3.54
3.54
59.34
2.28
0.88
0.68
50.49
7.38
13.78
15.62
Table K2: The result of tensile test in laboratory of Test B (international)
materials low-carbon
steel
austenitic
stainless steel
structural steel austenitic stainless
steel
high temper
steel
brand HR3(ISO) X2CrNi18-10 Fe510C(ISO) X2CrNiMo18-10 30NiCrMo-16
test piece rectangular
cross section
rectangular
cross section
circular cross
section
circular cross sec-
tion
circular cross
section
Rp0.2/(or ReL) (N/mm2)Total Average
UCr / %
UCL/ %
UCR/%
228.6
4.92
6.53
8.17
303.8
2.47
6.06
6.44
367.4
2.47
4.42
5.07
353.3
5.29
5.77
7.07
1039.9
1.13
1.64
1.99
Rm (N/mm2)Total Average
UCr / %
UCL/ %
UCR/%
335.2
1.14
4.86
4.09
594.0
2.63
2.88
2.98
552.4
1.25
1.42
1.90
622.5
1.36
2.71
3.02
1167.8
0.61
1.32
1.45
A/%
Total Average
UCr / %
Lo=80mm Lo=5d
38.41
10.44
52.47
3.81
31.44
6.41
51.86
3.82
16.69
7.07
43
UCL/ %
UCR/%
7.97
13.80
12.00
12.59
12.46
14.01
12.04
12.65
11.20
13.26
Z/%
Total Average
UCr / %
UCL/ %
UCR/%
71.38
2.05
1.71
2.68
77.94
1.99
5.25
5.62
65.59
2.45
2.11
3.23
Table K3: The result of tensile test in laboratory of Test C (domestic)
materials steel aluminum
alloy
aluminum
alloy
steel steel steel steel
brand st16 LF5M LY12CZ Q235A Q235 B480 40Cr
test piece rectangular
cross section
with two-side
machining
rectangular
cross section
with two-side
machining
rectangular
cross section
with two-side
machining
rectangular
cross section
with two-side
machining
circular cross
section with-
out machining
rectangular
cross section
with two-side
machining
circular cross
section with
machining (heat
treatment)
Rp0.2 (N/mm2)
Total Average
UCr / %
UCL/ %
UCR/%
145.59
7.57
14.06
15.97
166.28
2.97
3.62
4.69
325.18
3.35
4.57
5.66
984.32
1.97
-
1.97
ReH/(N/mm2)Total Average
UCr / %
UCL/ %
UCR/%
315.39
4.02
3.97
5.65
417.44
4.17
0.84
4.26
ReL/(N/mm2)
Total Average
UCr / %
UCL/ %
UCR/%
309.65
2.87
8.57
9.00
357.07
6.97
3.47
7.78
401.29
2.54
2.94
3.89
Rm/(N/mm2)Total Average
UCr / %
UCL/ %
UCR/%
287.94
2.37
3.43
4.16
301.01
1.15
3.61
3.79
451.67
3.16
2.79
4.22
456.96
1.85
6.07
6.33
513.23
4.87
2.87
5.66
527.22
1.88
1.76
2.58
1082.69
6.10
-----
6.10
A/%
44
Total Average
UCr / %
UCL/ %
UCR/%
46.06
7.36
13.52
15.40
25.03
10.64
6.40
12.42
33.50
9.51
6.31
11.41
29.88
11.38
13.59
18.01
33.53
10.64
7.86
13.23
15.59
14.17
7.89
16.22
Z/%
Total Aver-
age
UCr / %
UCL/ %
UCR/%
57.97
3.41
1.62
3.78
Appendix L20]
(Suggestive appendix)
Cross reference of new and old standard names of properties and symbols
The names of properties and symbols of the standard are different from those of former standard. They are
listed in table L1 and L2 for cross reference
L1: Cross reference of names of properties
Current standard Former standard
Names of Properties symbols Names of Properties symbols
Percentage reduction of area Z Percentage reduction of area Ψ
Percentage elongation after fracture
A
A11.3
Axmm
Percentage elongation after fracture
σ5
σ10
σxmm
Percentage total elongation after fracture At --- ---
Percentage elongation at maximum force Agt Percentage elongation under maximum force σgt
Percentage non-proportional elongation
at maximum force
Ag Percentage non-proportional elongation under
maximum force
σg
Percentage yield point extension Ae Percentage yield point elongation σs
Yield strength -- Yield point σs
Upper yield strength ReH Upper yield point σsU
Lower yield strength ReL Lower yield point σsL
Proof strength, non-proportional exten-
sion
Rp
such as Rp0.2
Proof stress, non-proportional elongationσp
such as σp0.2
Proof strength, total extensionRt
such as Rt0.5
Proof stress, total elongationσt
such as σt0.5
Permanent set strengthRr
such as Rr0.2
Permanent set stressσr
such as σr0.2
Tensile strength Rm Tensile strength σb
2Note:20] There is no this appendix in the international standard.
45
L2: Cross reference of symbols
Cross reference of symbols is in table L2.
Table L2: Cross reference of symbolscurrent standard former standard current standard former standard
46