gost 6996-66

UDC 621.791.053:620.17:006.354 Group B09

S T A T E S T A N D A R D O F T H E U S S R

Welded joints GOST6996-66

METHODS OF MECHANICALPROPERTIES DETERMINATION

(ST SEV 3521-82-ST SEV 3524-82,ST SEV 6732-89)

OKSTU 0909

Effective since 01.01.67

This standard establishes the methods for determination mechanicalproperties of of welded joint as a whole and its individual sections, as well as ofthe weld metal for all types of welding of metals and their alloys. (Revised version, Amendment No.2).

1. KINDS OF TEST AND FIELD OF APPLICATION

1.1. The standard establishes the methods of determination ofmechanical properties for the following kinds of tests:

a) static (short-time) tension test of metal on various sections of thewelded joint and weld metal;

b) impact bend test of metal on various sections of the welded joint andweld metal (on the cut specimens);

c) test of metal on various sections of the welded joint for resistance tostrain ageing;

d) measurement of metal hardness on various sections of the weldedjoint and weld metal;

e) test of welded joint for static tension;f) test of welded joint for static bend (fold);g) test of welded joint for impact breaking.

GOST 6996-66

1.2. The standard applies to the tests conducted when determining thequality of the products and welding materials, fitness of the welding methodsand conditions when determining qualification of welders and indicators ofweldability of metals and alloys.

1.3. Kinds of the tests, types of the specimens and application of methodare stipulated in the standards and specifications for the products determiningtechnical requirements to the products.

(Revised version, Amendment No. 3).

2. TAKING SPECIMENS

2.1. The specimens for the test are taken from the samples cut outdirectly from the inspected structure or from specially welded control joints forconducting the tests.

2.2. If the shape of the welded joint excludes the possibility of preparingthe specimens of the given type (parts of complicated configuration, pipes,etc.), then the specimens can be taken from specially welded flat control joints.

2.3. When preparing control joints, the weld preparation, grade andthickness of the parent metal, brands of welding materials, position of the weldin the space, initial temperature of the parent metal, welding and heat treatmentconditions should completely satisfy the conditions of manufacture of the articlebeing checked or special purpose of the test.

Welding of the control joints intended for the test of the welding materials(electrodes, welding wires, filler rods, fluxes, etc.), if no special requirementsare imposed, are carried out leaving each layer to cool down before applyingthe next one. The temperature to which the metal shall be cooled down isestablished by the standard or by other technical documentation.

(Revised version, Amendment No. 2 and No. 3)2.4. Dimensions of the plates for manufacture of the control joints are

determined by the requirements indicated below.2.4.1. For the control joints accomplished by arc, electro-slag and gas

welding from the flat elements the width of each welded plate, if not otherwisespecified in the standards of other technical documentation shoul be at least:

50 mm - for the thickness of metal up to 4 mm; 70 mm - for the thickness of metal over 4 mm up to 10 mm;100 mm - for the thickness of metal over 10 mm up to 20 mm;150 mm - for the thickness of metal over 20 mm up to 50 mm;200 mm - for the thickness of metal over 50 mm up to 100 mm;250 mm - for the thickness of metal over 100 mm.The width of the control joint accomplished from the round bars or

structural shapes shall be at least two diameters of the widths of the elements.2.4.2. The length of the welded edges of the plates is determined by the

dimensions and quantity of the specimens intended for manufacture taking intoconsideration the repeated tests, the allowances for the cut width andsubsequent machining and adding the length of the unused sections of theweld. The dimensions of the unused sections are assumed to be equal to:

GOST 6996-66

for the hand arc welding using the coated electrodes and the gas welding- at least 20 mm at the start and at least 30 mm at the weld end;

for the automatic and manual welding with any type of the backup exceptfor the flux, for the thickness of metal up to 10 mm - at least 15 mm at the startand at least 30 mm at the weld end, and for the thickness of metal over 10 mm- at least 30 mm at the start and at least 50 mm at the weld end;

for the automatic and manual submerged arc welding at the current of upto 1000 A for the electro-slag and arc welding with forced formation - at least 40mm at the start and at least 70 mm at the weld end;

for the automatic submerged welding at the current exceeding 1000 A -at least 60 mm at the weld start. In this case the length of the unused section atthe weld end is assumed to be equal to the length of the weld crater (thesection having incomplete cross section area).

(Revised version, Amendment No. 1).2.4.3. The dimensions of the plates for the control joints accomplished by

the welding methods and not indicated in item 2.4.1 are established by therespective specifications.

In the case of welding of the plates using the attached strips for bringingout the weld start and end, the specimens can be taken all over the entirelength of the control joint. The attached strips are manufactured from the samematerial as the plates.

The length of the attached strips should be not less than the dimensionof the unused sections of the weld (Ref. item 2.4.2).

2.5. The dimensions of the specimens cut out from the tested structureare determined by the quantity and dimensions of the specimens.

In the oxygen cutoff, the specimen dimensions are determined takinginto account the allowance for the subsequent machining to remove the metalsubjected to the thermal effect during cutting in the work section of thespecimens.

(Revised version, Amendment No. 2).2.6. Cutting of pieces for the specimens from samples and control joints

is recommended to be accomplished on the metal-cutting machine tools. It ispermissible to cut out the pieces on the shears, the dies by the oxygen, plasmaarc, electromechanical and other methods of cutting.

Allowance for the piece value to see that the working section of thespecimen does not contain metal, whose properties have changed as a resultof cutting, is determined depending on the method of cutting. The minimumallowance shall be:

for the thickness of metal up to 10 mm: the oxygen and plasma arccutting - 3 mm, the mechanical, including electromechanical, cutting - 2 mm;

for the thickness of metal over 10 to 30 mm: the oxygen cutting - 4 mm,the plasma arc cutting - 5 mm, the mechanical, including electromechanical,cutting - 3 mm;

for the thickness of metal over 30 to 50 mm: the oxygen cutting - 5 mm,the plasma arc cutting - 7 mm, the mechanical including electromechanicalcutting - 3 mm;

GOST 6996-66

for the thickness of metal over 50 mm: the oxygen cutting - 6 mm, theplasma arc cutting - 10 mm, the mechanical including electromechanical cutting- 3 mm.

In cutting pieces for the specimens from the metal when the properties inthe working portion of the specimen are not changed as result of cutting it ispermissible to decrease the above indicated allowances but not more thantwice.

The value of allowance for the cutting methods not listed above are givenin the standard technical documentation for the given type of the products ormethod of taking samples.

In manufacturing specimens it is necessary to take measures to preventchanging of the metal properties resulting from heating or cold working arisingduring machining.

(Revised version, Amendment No. 2 and No. 3).2.7. On the specimens, control joints and pieces of sheets and pipes, it is

necessary to show the direction of rolling of the parent metal relative to theweld.

(Revised version, Amendment No. 3).2.8. Straightening of the control joint or specimen taken from the tested

structure is inadmissible. It is permissible to straighten the finished specimensoutside their working section. In testing the welded joints of pipes the possibilityof the specimen straightening is specified by the standards or other technicaldocumentation.

If not specified otherwise in the standards or other technicaldocumentation, the sag ƒ on a length of 200 mm (Dwg. 1) should not exceed 10% of the metal thickness but not more than 4 mm.

Misalignment h of the planes of sheets at the butt joints (Dwg. 2) shouldnot exceed 15 % of the sheet thickness but not more than 4 mm.

2.9. Heat treatment, if this is specified in the standard technicaldocumentation, should be accomplished before finishing the specimens. Thesamples, control joints or the pieces cut out from them for the specimens canbe subject to heat treatment. In the case of normalizing or hardening, the heattreatment of the pieces for specimens is inadmissible.

GOST 6996-66

Dwg. 1

It is preferable to combine heat treatment of the control joints or thepieces for the specimens with heat treatment of the tested article. Theprocedure of accomplishing heat treatment when manufacturing the specimentsfrom the materials with σ в exceeding 1000 MPa (100 kgf/mm2) is specified inthe standard and technical documentation.


Dwg. 2

2.10. Marking of the samples, control joints and finished specimens canbe performed by any method so that the mark is located outside the workingportion of the specimen and remains intact after the test.

3. CONDITIONS OF TESTINGAND ASSESSMENT OF THE RESULTS

3.1. The specimens which have departures from the drawing dimensionsas regards their finish, as well as the mechanical damage in the workingportion, should not be submitted for testing and should be replaced by thesame number of new specimens manufactured from the same sample orcontrol joint. If the dimensions of the sample or control joint do not allow tomanufacture new specimens, a new sample should be cut out or a new controljoint welded.

If the results of the mechanical test comply with the requirements of thestandards or other technical documentation, in all cases, except for thearbitration tests, it is permissible to use the specimens having a lower surfaceroughness class.

(Revised version, Amendment No. 3).3.2. If not otherwise secified in the standards or other technical

documentation the test according to sections 4, 8 and 9 should be run with notless than two specimens; according to sections 5, 6 and 10 - not less than threespecimens; according to section 7 - with not less than four spots for eachsection of the welded joint. If the dimensions of the welded joint do not allow toarrange four spots, it is permissible to decrease their quantity in compliancewith the actual opportunities.


GOST 6996-66

3.3. The results of all kinds of tests are determined as an arithmeticmean of the results obtained in testing all specimens. If not otherwise specifiedin the respective standards or other technical documentation, then for all kindsof the tests, except for the static bend test and when measuring hardness, it ispermissible to decrease the test results for one speciment by 10 % relative tothe normative requirement, provided the arithmetic mean result meets thenormative requirements. The tolerable decrease of the results of the static bendtest and when measuring hardness should be specified in the respectivestandards or other technical documentation. In the impact bend test thetolerable decrease relative to the normative requirements should not exceed 5J/cm2 ( 0.5 kgf.m/cm2).

3.4. The tests specified in sections 7 to 10 should be accomplished atnormal temperature equal to (20+/-10) oC [(293+/-10) K]. The specimentemperature is assumed to be equal to the room temperature at which the testis accomplished. The tests specified in sections 4 to 6 should be run at thenormal temperature or according to the requirement specified in the respectivestandards or other technical documentation at decreased or elevatedtemperatures. When testing at the decreased or elevated temperatures thespeciment temperature is assumed to be equal to the temperature of theenvironment in which heating or cooling is accomplished. It is permissible todetermine the temperature on the check test specimens.

(Revised version, Amendment No. 1).3.5. The test results shall be considered unsatisfactory, if the

requirements stated in item 3.3 are not met or crystallization or cold cracks aredetected in the fracture of the speciment or on its surface (except for the caseswhen the presence of cracks is allowed according to the respective standardand technical documentation). If the test results are unsatisfactory, the testshould be repeated with a double quantity of the specimens. If in the fracture ofthe specimen, whose test results are considered to be unsatisfactory, defects ofparent metal or welded joint (except for cracks) are found, this specimen shouldbe excluded from the assessment and are replaced with a new sample.

The general results of the tests are determined on the basis of theindicators obtained during the repeated tests. The results of the repeated testsare considered to be final.

(Revised version, Amendment No. 2 and No. 3).

3.6. The methods for determining dimensions of the specimens, therequirements for the equipment for the tests, the conditions of testing and thedetermination of the results should comply with: in the static tension test atroom temperature - GOST 1497-84, at decreased temperatures - GOST 11150-84, at elevated temperatures - GOST 9651-84;

in the impact bend test at decreased, room and elevated temperatures -GOST 9454-78;

in measuring hardness - GOST 2999-75, GOST 9013-59 and GOST9012-59.

GOST 6996-66

Other requirements to the test conditions, determination of thedimensions of the specimens, the equipment for tests and calculation of theresults shall be specified in the standard or other technical documentation.

(Revised version, Amendment No. 2).3.7. The protocol in all kinds of the tests should contain:designation of this standard, thickness and grade of the parent metal,

method of welding, type of the joint, kind of heat treatment (if this isaccomplished), the specimen index (referring to the mark), the specimen type,the place of specimen taking, the results of the given kind of test of allspecimens, the presence of defects in the specimen fracture, in testing thewelded joints - the place of destruction (referring to the metal of the weld, to themetal of the heat-affected zone, to the parent metal). For the testsaccomplished according to sections 4 to 6 additionally indicated shall be thetemperature of the test; according to sections 5 and 6 - maximum power of theimpact testing machine; according to section 7 - the arrangement of hardnessmeasurement points.

(Revised version, Amendment No.2 and No. 3).

4. TESTING METAL OF VARIOUS SECTIONS OF WELDED JOINTAND WELD METAL FOR STATIC (SHORT-TIME) TENSION

4.1. In static (short-time) tension test of metal the followingcharacteristics of mechanical properties are determined:

physical yield point σ т, MPa (kgf/mm2) or nominal yield point σ 0,2,Mpa(kgf/mm2);

ultimate strength, σ в, MPa (kgf/mm2);elongation after fracture (on five-fold speciments) σ5, %;reduction of area after fracture, ϕ, %.The test is accomplished for the metal of the weld, metal of various

sections of the heat-affected zone of weld metal in all kinds of fuse welding.4.2. The shape and dimensions of the specimens used for the test

should comply with Dwg. 3 or 4 in table 1.It is permissible to increase the specimen diameter and its height.

GOST 6996-66

Type I, II, III

Dwg. 4

Table 1D i m e n s i o n s , m m

Type ofspecimen

do d K D h h1 R lo l L

IIIIII

3+/-0.16+/-0.110+/-0.2

---

0.030.030.04

61216

41010

22.53

11.53

153050

183660

30+/-161+/-186+/-1

IVV

6+/-0.110+/-0.2

1012

0.030.04

M12M16

1515

55

55

3050

3660

86+/-1110+/-1

Note. K - permissible difference between the largest and least diameters on the length ofthe specimen working portion.

(Revised version, Amendment No. 3)4.3. For the tests run at normal or decreased temperature, specimens of

all types are used. For tests at elevated temperatures the specimens of typesIV and V are used.

4.4. It is permissible to use proportional short cylindrical specimens ofanother diameter or type according to GOST 1497-84.

4.5. In tests run at elevated temperatures according to the requirementspecified in the standard or other technical documentation it is permissible touse proportional long cylindrical specimens No.2 and No.3 according to GOST9651-84.

If respective appliances are available, it is permissible to use thespecimens of types I, II and III for the tests run at elevated temperatures.

4.6. The net section of the specimens of all types should consistcompletely of the metal of the tested portion. The specimen heads are allowedto contain metal of other sections of the welded joint. The surface of the head isallowed to include one or two (parallel) flats as well as the unfinished surface ofthe weld or parent metal.

Dwg. 3Type IV, V

GOST 6996-66

The dimensions of the head in the place of the flat are as follows: for thespecimens of types I, II and III - not less than do+2; for the specimens of typesIV and V - at least d.

4.7. The place for cutting the specimens is marked using macrosectionsmade at the ends of the piece in compliance with the data of Tables 2 and 3. Allspecimens are arranged along the longitudinal axis of the tested portion.

In testing metal of the weld and weld metal with the section exceedingthe section of the specimen head it is permissible to mark out the place forcutting out the specimens without chemical cleaning of the piece on the outercontour of the weld meeting the requirements of Tables 2 and 3.

The arrangement of specimens in testing other sections of the metal ofthe weld or the metal of the weld zone is determined by the standards or othertechnical documentation.

4.6, 4.7. (Revised version, Amendment No. 3).

Table 2Item Type of weld Thickness of parent

metal, mmDiagram of specimens arrangement Instructions on cutting

out specimens1 Weld metal At least 12

Welding with coated electrodes in anatmosphere of shielding gas and gaswelding

q - at least 5 layers.Specimen is locatedabove the dash-dot line

2 Weld metal.Building-up isaccomplished on the ribof the plate, 20 mmthick. Length of the plateshould be at least 80mm. To hold the metal,the copper strips Ashould be installed

20


q - at least 5 layers, butnot less than 10 mm. Specimen should belocated above the dash-dot line

GOST 6996-66

Table 2, Continued

Item Type of weld Thickness of parentmetal, mm

Diagram of specimens arrangement Instructions on cuttingout specimens

3 Weld metal.Building-up should beaccomplished into thecopper mould. Theelements of the mouldcan be cooled by water


Number of layers shouldnot be less than six.Specimen is located longthe direction of welding.

4 Metal of single-layer andmultilayer fillets weldedwithout complete fusionof one of the elements

Arc and electro-slag welding

Thickness of weld Hshould not be less than6 mm

GOST 6996-66

Table 2, Continued



5 Metal of butt multilayerweld

At least 12


6 Metal of butt multilayerweld. Before welding theedges are built up withat least three layersusing the testedmaterials

At least 12


The specimen netsection should notcontain metal built up onthe edges of the strips

GOST 6996-66

Table 2, Continued



7 Metal of butt multilayerweld with preliminarybuilding-up the edgesand the backing at leastin three layers. Forbuilding-up use is madeof the tested materials.The width of the backingis 30 mm

At least 20 Gap between butting edges shall be 16mm


The specimen netsection should notcontain metal built up onthe edges of the stripsand on the backing

GOST 6996-66

Table 2, Continued



8 Metal of butt one-sidedand two-sided symmetricand asymmetric single-layer and multilayerwelds

From 5 to 15

Arc welding withforced formation

Arc welding

Arc welding

GOST 6996-66

Table 2, Continued



9 Metal of two-sided andone-sided fillets withcomplete fusing of theside


Thickness of weld Hshould not be less than 6mm. If the thickness ofthe weld is sufficient, thearrangement of thespecimens cancorrespond to theposition 12 of Table 2 orposition 2 of Table 3


GOST 6996-66

Table 2, Continued



10C = 0.5D+2 mm

11 From 16 to 35

12 C = 0.5D+2 mm

13

Metal of one-sided andmultilayer butt welds

From 30 to 60 C = 0.5D+2 mm

Arc welding

Electro-slag welding

Arc welding


GOST 6996-66

Table 2, Continued



14 C = 0.5D+2 mm

15Metal of one-sided andmultilayer butt welds From 61 to 350


C=0.5D+2 mmArc welding

GOST 6996-66

Table 3

Item Type of weld Thickness ofsecond weld H, mm


1 From 16 to 35

Arc welding

C = 0.5D+2 mm

2

Metal of two-sidedsingle-layer andmultilayer butt welds

From 36 to 60

Arc welding

C=0.5D+2 mm

GOST 6996-66

Table 3, Continued

Item Type of weld Thickness ofsecond weld H, mm


3 Metal of two-sidedsingle-layer andmultilayer butt welds

From 61 to 1505

Arc welding

C = 0.5D+2 mm

Notes to tables 2 and 3:1. a - thickness of metal, mm; D - diameter of the specimen head, mm;

C - distance from the weld surface to the specimen axis, mm.2. For the one-pass welds the specimens cut out from various sections of the weld practically have similar mechanical properties. For the

multiple-pass welds the mechanical properties in various sections of the weld are different. The place of cutting-out of the specimens from the multiple-pass welds is specified in the standards or other technical documentation. When special instructions are not available, the specimens are cut out at theweld surface.

3. For the welded joints made from the rounds the diagram for taking specimens remains the same.4. The pieces given in items 1 to 3, 5 to 7 of Table 2 are intended for checking quality of the welding materials.5. If the standards or other technical documentation have no other instructions, then in the case of two-sided welding the specimens for testing

are cut out from the second weld.

GOST 6996-66

5. IMPACT BEND TEST OF METAL OF VARIOUS SECTIONSOF WELDED JOINT AND WELD METAL

(ON THE NICKED SPECIMENS)

5.1. The impact bend test is run to determine the impact strength orimpact work, or percentage relation of brittle and viscous components of thefracture surface for the metal of the weld, weld metal, fusion zone and varioussections of the weld zone with the thickness of the parent metal of 2 mm andmore.

Impact strength is determined in J/cm2 (kgf!m/cm2), if not otherwisespecified in the respective standards or other standard technicaldocumentation.

(Revised version, Amendment No. 2 and No. 3).5.2. For testing use is made of the specimens whose shape, dimension

and surface condition correspond to those indicated in Dwg. 5 (the specimenswith U-shaped nick) or in Dwg. 6 (the specimens with V-shaped nick). Thespecimens with V-shaped nick are preferable.

Type VI

a - thickness of parent metal, mmDwg. 5

Type VIII

Type VII

GOST 6996-66

In compliance with the requirement indicated in the standard technicaldocumentation it is permissible to use specimens of type VI (Ref. Dwg. 5) withthe nick shown in Dwg. 7 or 8.

Type IX

Dwg. 7 Dwg. 8

5.3. The designation of impact strength or impact work should include:the symbol of the impact strength (KC) or the impact work (K); the kind of thenick (concentrator) (U, V); the testing temperature (the temperature of +20 oC isnot indicated); the maximum energy of pendulum impact (maximum energy in300 J is not indicated); specimen type (VI and IX types are not indicated);the place of nick location ( Ш - weld, ЗС - fusion zone, ЗТВ - heat-affectedzone, t - distance between the fusion boundary and the nick axis). Value t isspecified in the standards or other technical documentation. If the nick islocated transverse to the metal of the weld, the fusion zone or the heat-affectedzone, letter П is put at the end of designation.

Type X

Type XI


GOST 6996-66

E x a m p l e s o f r e f e r e n c e d e s i g n a t i o n s :1. Impact strength determined for the type VII specimen at a temperature

of +100 oC with the maximum energy of pendulum impact of 150 J, with the U-shaped nick located in the fusion zone: KCU+100 150 УПЗС.

2. Impact strength determined for the type XI specimen at a temperatureof minus 40 oC with the maximum energy of pendulum impact of 50 J, with theV-shaped nick located in the heat-affected zone at a distance of (t mm) fromthe fusion boundary to the nick axis: KCV-40 50 XI ЗТВt.

3. Impact strength determined for the type VI specimen at a temperatureof +20 oC with the maximum energy of pendulum impact of 300 J with the U-shaped nick located on the metal of the weld: KCUШ.

4. Impact strength for the type IX specimen at a temperature of +20 oCwith the maximum energy of pendulum impact of 300 J with the V-shaped nicklocated transverse to the metal of the weld: KCVШ П.

5.2, 5.3. (Revised version, Amendment No.3).5.4. Specimens of different types display different test results which are

incomparable between themselves. In certain cases specific conversion factorscan be established experimentally.

5.5. In impact bend test use is made of specimens with the maximumpossible width for the given thickness of the parent metal. With this in view, forthe thickness of the parent metal of 11 mm and more specimens of type VI orIX should be used, for the thickness of the parent metal of 6 to 10 mm -specimens of type VII or X, for the thickness of the parent metal of 2 to 5 mm -specimens of type VIII or XI. Use of the specimens of types VII and X instead ofthe specimens of types VI and IX and the use of specimens of types VIII and XIinstead of specimens of types VII and X or VI and IX is admissible only in thecomparative tests when for one of the objects of comparison employment of athin specimen is stipulated by the thickness of the parent metal.

When cutting out specimens of types VI and IX from the welded jointmade from the parent metal 11 mm thick and specimens of types VII and Xmade from the parent metal 6 mm thick, the unfinished parent metal can befound on two surfaces of the specimen. The surface of the parent metal ofspecimens of types VIII and XI should not be finished.

On all specimens camber of the weld is removed to the level of theparent metal. Misalignment of the edges in the welded joint, if any, is removedmechanically (Ref. Dwg. 2).

(Revised version, Amendment No. 2 and No.3)5.6. Depending on the purpose of the test, the nick shall be located on

the metal of the weld (Dwgs 9 and 10), on the fusion zone (Dwg. 11) and invarious sections of metal of the weld zone at distance t from the fusionboundary (Dwgs 12 and 13).The place of location of the nick and distance t fomthe fusion boundary to the nick axis is specified in the standard technicaldocumentation.

GOST 6996-66

Dwg. 9 Dwg. 10

In testing the metal of the weld zone in pressure welding, the distance tis measured from the weld axis.

(Revised version, Amendment No. 2 and No.3).5.7. The place of the nick is marked with respect to the macrosections

located on the edges of the specimen or the piece for the specimens. Locationof the nick should comply with item 5.6. All specimens are cut out transverse tothe tested section of the welded joint. Orientation of the nick for the specimensof types VI and IX should comply with Dwgs 9, 11 and 12, for specimens oftypes VII, VIII, X and XI should comply with Dwgs 10 and 13.

Orientation of the nick for specimens of types VI and IX is specified inthe standard technical documentation. Cutting of the specimens and pieces forthem should be accomplished with reference to Tables 4 and 5.

The arrangement of specimens in testing the metal of the weld zone forthe butt joints and the metal of the weld and the weld zone in testing the T-joints and lap joints is specified in the standards or other technicaldocumentation.

Arc welding

Electro-slag welding andarc welding with forcedformation

Arc welding

GOST 6996-66

Arc weldingDwg. 13

Arc welding

Electro-slag welding and arcwelding with forced formation

Arc welding according tospecial procedure

Electro-slag welding and arcwelding with forced formation

Arc welding

Dwg. 11 Dwg. 12

GOST 6996-66

Table 4


Diagram speciments arrangement Instructions on cuttingout specimens

1 Weld metal.Width of the strip onwhich building-up isaccomplished is at least80 mm

At least 12


q - at least 5 layers.Specimen is to belocated above the dash-dot line

2 Metal of butt multiple-pass welds

At least 12


C - at least 1.5 mm

GOST 6996-66

Table 4, Continued



3 Metal of butt multiple-pass welds. Beforewelding edges should bebuilt up at least in threelayers. For building-upuse is made of thetested materials.

At least 12


C - not more than1.5 mm

4 Metal of butt multiple-pass welds. Beforewelding, edges andbacking are built up atleast in three layers. Forbuilding-up use is madeof the tested materials.

At least 20 Gap between butt edges


C - not more than1.5 mm

GOST 6996-66

Table 4, Continued



5

6

7

8

Metal of butt welds of alltypes

From 2 to 17

Arc welding with forced formation

Resistance butt andpressure-gas welding

Arc and gas welding

Arc and gas welding

GOST 6996-66

Table 4, Continued



9

10

From 18 to 40


C - from 1 to 3 mm

11

C - from 1 to 3 mm

12

Metal of one-sided, one-pass and multiple-passbutt welds

From 41 to 60


C - at least 8 mm

Arc welding

Arc welding

GOST 6996-66

Table 4, Continued



13 C - from 1 to 3 mm

14

Metal of one-sided, one-pass and multiple-passbutt welds

From 61 to350


C - at least 8 mm

Arc welding

GOST 6996-66

Table 5



1

From 18 to 40

Arc welding

C - from 1 to 3 mm

2

Metal of two-sided,single-layer and multiple-layer butt welds

From 41 to 60

Arc welding

From 1 to 3 mm

GOST 6996-66

Table 5, Continued


Diagram of specimens arrangement Instructions on cuttingoutspecimens

3Metal of two-sided,single-layer and multiple-layerbutt welds

From 61 to 350

Arc welding

C - from 1 to 3 mm

Notes to Tables 4 and 5.1. a - thickness of parent metal, mm;

C - distance from the specimen surface to the specimen (piece) edge, mm.2. For the single-layer welds the specimens cut out from various sections of the weld practically have similar impact strength. For the multiple-

layer welds the impact strength of the metal in various sections of the weld differ from one another. The place of cutting the specimens is specified in thestandards or other technical documentation. If such instructions are not available, the specimens are cut out at the weld surface.

3. If the standards or other technical documentation does not contain special instructions, then for the two-sided welds the specimens should becut out from the second weld. For the two-sided multilayer welds made with alternating application of passes the specimens shall be cut out from theside of the last pass.

4. The pieces given in items 1 to 4 of Table 4 are used for checking quality of the welding materials.

GOST 6996-66

6. TESTING OF METAL OF VARIUOS SECTIONS OFWELDED JOINT FOR RESISTANCE TO

STRAIN AGEING

6.1. Resistance to strain ageing is characterised by the change of theimpact strength of the metal subjected to ageing in comparison with its impactstrength in the initial state. Resistance to strain ageing of the metal isdetermined by the ratio of these values expressed in per cent or by the absolute(standard) value of the impact strength after ageing. The test is carried out forthe metal of the weld and various sections of metal of the weld zone.

6.2. The pieces shall be subject to artificial ageing following the method:tensile deformation at the rate to obtain (10+/-0.5) % of permanent elongationwithin the limits of the design length l, restricted by the center-prick or marks. Itis recommended to apply marks every 10 mm to the surfaces of the specimensfor checking uniformity of deformation over the length of the design portion.

After elongation the piece shall be subject to uniform heating to atemperature of 250 oC (523 oK) during 1 hour with subsequent cooling in the air.From the effective portion of the pieces in Dwgs 14, 15 or 17 the specimens oftype VI or IX shall be taken, and in Dwg 16 - type VII or X. The axis of the nickshall coinside with the axis of symmetry of the weld. The specimens takingdiagram with the nick located in other sections of the welded joint is specified inthe standards or other technical documentation.

The method of ageing stipulated by this item shall be used for thewelded joints of steels. The method of ageing for other metals and alloys aswell as the heating temperature or magnitude of deformation for the joints ofsteel is specified in the standards or other technical documentation.

6.3. Subjected to strain ageing shall be the pieces taken from the buttjoint in compliance with Dwg. 14 or 15 and Table 6. The axis of symmetry of thepiece shall coinside with the longitudinal axis of the weld or with the axis of thefuture nick (if the test is accomplished not for metal two). Location of the nickaccording to Dwg. 15 is used for the electro-slag welding and in the casesspecified in item 5.6. The pieces according to Dwg. 16 are used in testing ofwelded joints of metal at least 12 mm thick. According to the requirementspecified in the standards or other technical documentation it is permissible toemploy the pieces given in Dwg. 17 for the welded joints accomplished by theelectro-slag welding process.

6.4. The length of the gripping portion h of the pieces is determineddepending on the design of the testing machine.

6.5. Index “cт” should be added to the reference designation of thespecimen specified in item 5.3 (for example, KC cт Ш, КС ст Ш).

GOST 6996-66

Table 6



1

2

3

All butt welds From 6 to 17

Arc welding with forced formation

Arc welding

Arc welding

GOST 6996-66

Table 6, Continued



4C - from 1 to 3 mm

5

More than 20

6

One-sided, single-passand multiple-pass buttwelds

From 56 to 350


C - at least 8 mm.Cutting of the piecesaccording to this diagramshould be specified inthe standards or othertechnical documentation.Specimens shall betaken according to Dwg.17

Arc welding


GOST 6996-66

Table 6, Continued



7 Two-sided, single-layerand multilayer butt welds

More than 17

Arc welding

C - form 1 to 3 mm

Note. a - thickness of parent metal, mm; C - distance from the metal surface to the piece edge, mm.

GOST 6996-66

Dwg. 17

(Revised version, Amendment No. )

Dwg. 14

Dwg. 15

Dwg. 16

GOST 6996-66

7. MEASURING OF METAL HARDNESS IN VARIOUSSECTIONS OF WELDED JOINTS AND WELD METAL

7.1. Hardness is measured in the welded joint cross-section incompliance with Dwgs 18, 18a and 19.

7.2. Hardness is determined according to Vickers (HV), Brinell (HB) andRockwell - scales A, B and C (HRA, HRB and HRC) showing preference toVickers.

Note. In all cases except for position VII the hardness measurement lines pass throughall sections of the welded joint. C - from 2 to 4 mm, C1 - from 10 to 15 mm;a - thickness of parent metal, mm; H - thickness of fillet weld, mm; q - preparatory section atleast 5 layers thick; q1 - hardness measurement section at least six layers thick. Value C for thefillet welds having concave or convex surface is determined from the place of maximumconcavity or convexity.

Dwg. 18

VIII

GOST 6996-66

Dwg. 18a

Vickers hardness measurement is performed according to GOST 2999-75. Depending on the strength of the metal of the welded joint sections and thewidth of the heat-affected zone the load to be applied to the indenter shouldmake 98 H (HV10) or 49H (HV5). If the respective instructions are available inthe standards or other technical documentation, Vickers hardness should bemeasured. In such measurements the load on the indenter can vary from 0.04to 4.9 H.

Brinell hardness measurement is made according to GOST 9012-59using a steel ball, 2.5 or 5.0 mm diameter.

Rockwell hardness measurement is accomplished according to GOST9013-59 with sphere conical diamond indenter (scale A and C) or with steel ballindenter, 1.5875 mm diameter.

7.3. Hardness shall be determined for the joints obtained as a result offusion or pressure welding from the steels of various qualities and other metalconstructional materials at least 1.5 mm thick.

Hardness of the parent metal, of various sections of the heat-affectedzone and the metal of the weld should be measured along one or several linesindicated in Dwg. 18. If the joint is made from the metals of various qualities,then hardness should be measured for each of them.

In measurements made in close proximity to the fusion boundary it isrecommended to make 2 to 3 measurements in compliance with position I ofDwg. 18a or additional measurements according to position 11 of Dwg. 18a.

It is permissible to make measurements on the sections of the weldedjoint indicated in Dwg. 19.

GOST 6996-66

Dwg. 19

7.4. Vickers hardness is measured on the microsections or thespecimens with polished surface provided the outline of the weld is seenwithout chemical etching. Surface roughness of such specimens should befrom 0.40 to 0.63 µm. Brinell or Rockwell hardness measurements should bedone on the macrosections or on the specimens with ground surface providedthe outline of the weld is seen without chemical etching. Surface roughness ofsuch specimens should be from 1.25 to 2.00 µm. The working and bearingsurfaces in the specimens should be parallel.

7.5. Hardness of the butt and fillet welds made by arc welding should bemeasured for the thickness of the parent metal or the fillet weld from 1.5 to 9mm in compliance with position VIII of Dwg. 18 on one dotted line; for thethickness from 9 to 25 mm in compliance with positions I and III of Dwg. 18 ontwo solid lines; for the thickness from 26 to 60 mm - in compliance withpositions II or III of Dwg. 18 on two solid lines and one dotted line.

With the thickness of the parent metal or the fillet weld exceeding 60mm, the hardness measurement diagram is specified in the standards or othertechnical documentation.

Hardness of the welded joints made by the electro-slag welding ismeasured in compliance with position IV of Dwg. 18. The member ofmeasurement points within the heat-affected zone shall be at least 10.

Hardness of various sections of the weld metal is to be measured incompliance with position V of Dwg. 18.

Hardness of the welded joints made by welding shall be measuredin compliance with position VI of Dwg. 18.

Hardness of the weld metal in checking quality of the welding materialsshall be measured in compliance with position VII of Dwg. 18.


GOST 6996-66

8. STATIC TENSION TEST OF WELDED JOINT

8.1. This test is run to determined the strength of the weakest section ofthe butt or lap joint or the strength of the metal of the weld in the butt joint.


A . D e t e r m i n i n g t h e s t r e n g t h o f t h e w e a k e s ts e c t i o n o f t h e b u t t a n d l a p j o i n t s .

8.2. In the static tension test of the welded joint, the ultimate strength ofthe weakest section is to be determined. Determination of the ultimate strengthis accomplished according to GOST 1497-84. In testing, the place of thespecimen failure is determined (referring to the metal of the weld, to the metalof the weld zone, to the parent metal).

(Revised version, Amendment No. 1 and No.2).

8.3. The test is accomplished, as a rule, on the specimens whosethickness or diameter equals the thickness or diameter of the parent metal. Intesting the welded joint or plates of various thickness, the thicker plate shouldbe machined to the thickness of the plate which is thinner.

After machining the thickness of the thicker element should be not morethan 6.3 µm.

8.4. The shape and the dimension of the flat specimens for testing of thebutt joints should correspond to Dwgs 20, 21 or 21a and Table 7. It ispermissible to use cylindrical specimens of types I, II, III, IV and V. In thesespeciments the metal of the weld should be in the center of their workingportion. It is permissible to use the specimen according to GOST 1497-84.

In testing high strength materials it is permissible to change constructionof the specimen gripping portion.

Type XII

Dwg. 20

GOST 6996-66

Type XIII

Dwg. 21a

Dwg. 21

Type XIIIa

GOST 6996-66


Specimen type Specimen thickness Width of specimenworking portion, h

Width ofspecimengripping

portion, h1

Length ofspecimenworkingportion, l

Total length ofspecimen, L

Dwg. No.

XII,XIII Up to 6Over 6 to 10, incl.Over 10 to 25,incl.Over 25 to 50,incl.Over 50 to 75,incl.

Equals parentmetal thickness

15+/-0.520+/-0.525+/-0.530+/-0.535+/-0.5

2530354045

5060100160200

l + 2h 20 or 21

XIIIa Equals or is lessthan 20Over 20 to 40

Over 40

Equals metalthicknessEquals metalthickness or 2020 or 10

Not less than 1/2specimenthickness but notless than 10 andnot more than 50

h + 12 lIII + 60 Equals or ismore than200

21a

Notes:1. h - maximum width of the weld.2. Length of specimen gripping portion h shall be determined depending on the testing machine design.3. Dimensions of specimens of types XII and XIII with the parent metal thickness more than 75 mm are determined by the standards or other

standard documentation.4. The length of the working portion of the specimen can be increased if the design of the testing machine does not allow to test the specimen of

the assigned length.


GOST 6996-66

8.5. The shape and the dimensions of the cylindrical specimens fortesting the butt joints of the bars of round or polyhedral section mustcorrespond to those indicated in Dwgs 22 and 22a and in Table 8. For testingthe butt joints from the reinforcing-bar steel use is made of unfinishedspecimens with removed increased thickness.

Type XIV

Dwg. 22a

(Revised version, Amendment No. 3).8.6. The increased thickness of the weld should be removed by

machining to the level of the parent metal. In removing the increased thicknessit is permssible to remove the parent metal over the entire surface of thespecimen to the depth of 15 % of the metal thickness or the diameter of the barbut not more than 4 mm. The parent metal should be removed from the surfaceof the specimen only on the side from which the increased thickness of theweld is removed or on which there is a shoulder (Ref. Dwg. 2). Planing of theincreased thickness should be performed transverse to the weld. Sharp edgesof the flat specimens within the working portion shall be rounded off at a radiusof not more than 1.0 mm by furnishing with a file along the edge. It ispermissible to plane the increased thickness along the weld with subsequentremoval of scratches. Roughness of surface Rz in the places where theincreased thickness is removed must not exceed 6.3 µm.


Dwg. 22

Type XIVa

GOST 6996-66


Specimen type Diameter of a round bar ordiameter of a

circumference inscribedinto polyhedral bar, B

Diameter of specimengripping portion d1

Diameter of specimenworking portion d

Length ofspecimen working

portion l

Specimentotal length L

Dwg. No.

XIV Up to 10Over 10 to25Over 25 to 50Over 50 to 75

- Dc or B60100160200

l +2h 22

XIV Unlimited Dc or B but not morethan 40

0.8 d1 lIII +60 ≥200 22a

Notes:1. lIII - maximum width of the weld.2. The length of the gripping portion h is determined depending on the design of the testing machine.3. With Dc more than 75 mm the dimensions of the specimen of type XIV are determined by the standards or other standard technical

documentation.

GOST 6996-66

8.7. It is permissible to test specimens of types XII, XIII, XIIIa and XIVwithout removal of the increased thickness provided this is stipulated in thestandard technical documentation.

In this case the magnitude of the specimen sectional area outside theweld must be included into the ultimate strength formula (GOST 1497-84).


8.8. If the power of the breaking machine is insufficient it is permissibleto test the flat specimens (Dwg. 23) or cylindrical specimens (Dwgs 24 or 25) .The size of the gripping portion of the specimen h shall be determineddepending on the design of the testing machine. The diagram of arrangementof the pieces for specimens of types XVI and XVII is given in Tables 9 and 10.

It is permissible to use the cylindrical specimens having other nominaldiameters and another type of the gripping portion in compliance with GOST1497-84. It is admissible to test specimens of types XII to XVII having a lowerclass of finish provided that the mechanical properties of the tested metal meetall requirements.

Type XV

Dwg. 24 Dwg. 25

a - thickness of parent metal, mm

Dwg. 23

Type XVI Type XVII

GOST 6996-66

Table 9

Item Type of weld Thickness ofpartent metal or

diameter ofspecimen, mm

Diagram of pieces arrangement Instructions on cutting ofpieces

1 For specimens oftype XVI from 25

to 50

2

3

All butt welds

For specimens oftype XVII or 30 to

70


For butt resistance andpressure-gas welding thediagram for specimencutting is similar

Arc welding

Arc welding

GOST 6996-66

Table 10


Pieces arrangement diagram Instructions on cutting ofpieces

1

2

For specimens oftype XVI from 51 to

75

3

All butt welds

For specimens oftype XVII from 71

to 100


C - from 1 to 3 mmFor butt resistance andpressure-gas welding thediagram for specimenscutting is similar

Arc welding

Arc welding

GOST 6996-66

Table 10, Continued


Pieces arrangement diagram Instructions on cutting ofpieces

4 For specimens oftype XVI over 75

5

6

All butt weldsFor specimens oftype XVII over 100


C - from 1 to 3 mm

N o t e t o t a b l e s 9 a n d 1 0 .a - thickness of parent metal, mm; C - distance from the surface of metal to the edge of the piece, mm

Arc welding

Arc welding

GOST 6996-66

8.9. To check strength of the welded joints of pipes segmentalspecimens are used indicated in Dwg. 20 or 21, or 21a, as well as cylindricalspecimens in the form of lengths of pipes indicated in Dwg. 26 or 26a, or 27.The specimens of types XII, XIII, XIIIa are not straightened. The naturalcurvature of the pipe determines their shape in cross-section.

Type XVIII

Dwg. 27

The segmental specimens are cut out when the pipe diameter exceeds20 mm.

The cylindrical specimens of types XVIII and XVIIIa are cut out when thepipe diameter is below 100 mm. If respective equipment is available, thespecimens of this type are also cut out when the pipe diameters are larger.

Dwg. 26

Type XVIIIa

Dwg. 26a

Type XIX

GOST 6996-66

In testing specimen of type XIX its maximum diameter is determined by powerof the testing machine. The value of the cross sectional area of the pipe outsidethe weld is included in the ultimate strength formula (GOST 1497-84) for thespecimens of this type. In specimens of types XVII, XIII and XIIIa the weldcamber is removed on two sides. In the specimens of types XVIII and XIX theweld camber shall not be removed, in the specimens of type XVIIIa the weldcamber shall be removed only from the external side. In compliance with therequirements outlined in the standard technical documentation it is permissibleto test specimens, type XVIII with the weld camber removed from the externalside. If the power of the testing machine is insufficient, it is permissible to usespecimens of types I to V. The metal of the weld is to be located in thespecimen center.

8.10. The ends of specimens of types XVIII and XVIIIa shall be preparedfor testing by using cylindrical plugs (specimens of type XVIIIa) or flattening(specimens of types XVIII and XVIIIa). The distance between the inner ends ofthe metal plugs should be equal to l+2D. The distance from the weld axis to thestart of the flattened portion should be at least two diameters of the pipe.


8.11. The welded joints accomplished by spot welding and plug weldsare tested for shear by subjecting the specimen given in Dwg. 29 to tension orfor breaking-off subjecting the specimen given in Dwg. 30 to tension. In allcases when testing the plug welds the specimen width must be equal to 50 mm.

The specimen dimensions must be as in Table 11.

Table 11

D i m e n s i o n s , m m

Thickness of parent metal, a Specimen width b, min

Up to 1, inclusiveOver 1 to 2, inclusiveOver 2 to 3, inclusiveOver 3 to 4, inclusiveOver 4 to 5, inclusiveOver 5

202530354045


8.12. In testing, the breaking load on the weld spot is determined innewtons (N), kilograms (kg).

GOST 6996-66

Type XX

Dwg. 30

__________________∗ Dwg. 28 omitted.

a - thickness of parent metal, mm; h - length of thegripping portion (to be selected depending on the

testing machine design), mm; l - length ofspecimen working portion, mm.

Dwg. 29∗

Type XXI

GOST 6996-66

8.13. To prevent bending, specimens of type XXI should be secured inthe special appliance. The appliance must provide stiffness of the specimenand the possibility of testing the specimen on the breaking machines.

8.14. The welded joints of the plates made by the seam welding aretested for shear by subjecting the specimens given in Dwg. 31 or 32 to tension.

With metal thickness up to 1.0 mm specimens of type XXIII are tested.With metal thickness over 1.0 mm the specimen type shall not be determined.In testing, the breaking load on the specimen is determined in kilograms(newtons).

Type XII

Dwg. 31

Type XXIII

Dwg. 32

GOST 6996-66

8.15. Cutting of specimens of types XX, XXII and XXIII from the controljoints welded by spot or seam welding is made according to Dwg. 33. Weldspots are made with a pitch to provide the possibility of cutting out thespecimens of the assigned dimensions.

It is permissible to weld the specimens using one weld spot incompliance with Dwg. 29.

Б . D e t e r m i n i n g s t r e n g t h o f m e t a l o f t h e w e l d i nb u t t j o i n t

8.16. In testing strength of the metal of the weld in the butt joint itsultimate strength is determined.

8.17. The thickness of specimen of type XXIV should be equal to theparent metal thickness. The diameter of the gripping portion of specimen oftype XXV should equal to the parent metal thickness or the diameter of thewelded elements.

(Revised version, Amendment No.1).

Dwg. 33

8.18. The shape and dimensions of the flat specimen must be as shownin Dwg. 34 and Table 12.

Type XXI

Dwg. 34

lines of cut

GOST 6996-66

Table 12

D i m e n s i o n s , m mParent metal

thicknessWidth of

specimengripping

portion b1

Width ofworking portionof specimen b

Radius ofcurvature

R

Length ofspecimen

working portionl

Total lengthof specimen

L

Up to 6 25 15+/-0.5 6+/-1 40

Over 6 to 10 30 20+/-0.5 12+/-1 60

Over 10 to 25 38 25+/-0.5 20+/-2 70 L = l+2h

Over 25 to 40 45 30+/-0.5 25+/2 90

Over 40 to 50 55 35+/-0.5 30+/-2 110

Notes:1. The length of the specimen gripping portion h is determined depending on the testing

machine design.2. The dimensions of the specimen with the thickness of metal over 50 mm are

determined by the respective specifications.

8.19. The shape and dimensions of the cylindrical specimen mustcorrespond to Dwg. 35 and Table 13.

Type XXV

Dwg. 35

GOST 6996-66

Table 13

D i m e n s i o n s , m mDiameter of

specimen grippingportion d1

Diameter ofspecimen working

portion d

Radius ofcurvature R

Length ofspecimen

working portion l

Total length ofspecimen L

Up to 5 40

Over 5 to 10 60

Over 10 to 15

d=0.6d1

70

Over 15 to 30 90

Over 30 to 50

d=0.7d1

R=0.5d1

110

L = l+2h

Notes:1. The length of the specimen gripping portion L is determined depending on the testing

machine design.2. The dimensions of the specimen with the thickness of metal over 50 mm are

determined by the respective specifications.

8.20. The lateral axis of specimens of types XXIV and XXV mustcoinside with the weld axis. For one-sided welds the specimen lateral axis ismarked on the narrow portion of the weld (for the electric arc welding) or on thefin (for resistance or pressure-gas welding).

For two-sided welds the lateral axis is marked after grinding andchemical etching of the specimen side surfaces on the macrosection or in thecenter of camber of the weld welded on the second side.

8.21. The ultimate strength is determined from the formula:

σв =k P/F,

where σв - ultimate strength, Mpa (kgf/mm2) ;k - correction factor;P - maximum force, H (kgf);F - specimen cross-sectional area in the least cross section before thetest, mm2 (m2).

For the carbon steels and low-alloyed structural steels factor k isassumed to be equal to 0.9. For other metals k is determined by respectivetechnical documentation.

8.22. Camber of the weld for specimens of type XXIV shall be removedin compliance with item 8.6.

8.18 to 8.22. (Revised version, Amendment No.3).

GOST 6996-66

9. TESTING OF THE WELDED JOINT FOR STATIC BEND

9.1. Tests are performed for the butt joints. In testing, the ability of thejoint to take the assigned size and shape of the bend is determined. This abilityis characterised by the bend angle α (Dwg. 36) at which the first crackpropagating in the course of testing occurs in the zone of tension. If the lengthof cracks arising in the course of testing within the specimen tension zone doesnot exceed 20 % of its width but not more than 5 mm, then it is not a symptomfor rejection. The place of formation of a crack or destruction is also determined(referring to the metal of the weld, the metal of the weld zone or the parentmetal).

Depending on the requirements established by the respective standardtechnical documentation, the test shall be performed until the design bendangle is reached or the bend angle at which the first crack being the reason forrejection is formed, until the specimen sides become parallel or come incontact. The bend angle as testing up to the formation of the first crack ismeasured in the unstressed state with an error of +/-2 o.

Dwg. 36


9.2. The shape and the dimensions of the flat specimens must complywith those indicated in Dwgs 37, 38, 38a and in Table 14.

Thickness of specimens of the types XXVI, XXVII and XXVIII with thethickness of the parent metal ≤50 mm must be equal to the parent metalthickness. With the metal thickness exceeding 50 mm the specimen thicknessis determined in the standard technical documentation. It is permissible to cutout specimens of types XXVIa, XXVIIa and XXVIIIa whose thickness is lessthan the parent metal thickness in various sections of the welded joint cross-section. Different normative requirements are established for the results oftesting various specimen types.

GOST 6996-66

Camber of the weld on both sides of the specimen is removedmechanically to the level of the parent metal with surface roughness up to6.3 µm. If not otherwise specified in the standard technical documentation, inthe process of removal of the increased thickness the cuts of the parent metalshall be also removed. Planing of the increased thickness on the specimens oftypes XXVI and XXVIa shall be accomplished lengthwise of the weld and on thespecimens of types XXVII, XXVIIa, XXVIII and XXVIIIa - crosswise. It ispermissible to plane the increased thickness in any direction with subsequentremoval of scratches. Within their working portion the edges of the specimensmust be rounded off at a radius of ≥0.1 of the specimen thickness but not morethan 2 mm by smoothing with a file along the edge.

Types XXVI, XXVIa Types XXVII, XXVIIa, XXVIII

Dwg. 38a

After final finish the axis of the specimen located transverse to the weldshould be on its center.

Dwg. 37 Dwg. 38

Type XXVIIIa

GOST 6996-66

Table 11

D i m e n s i o n s , m m

Specimentype

Thickness ofparent metal and

specimen a

Specimen width h Total length of specimenL

Length of specimenworking portion l

Dwg. No.

5 a+15XXVIOver 5 to 50 a+20

2.5D+80 0.33L 37

XXVIa Up to 25 lIII+10 but not less than 20 Not more than 250 Not to be specifiedXXVII Up to 50 1.5a but not less than 10 2.5D+80 0.33LXXVIIa Up to 25 Not less than 1.5a but not less

than 20 and not more than 50Not more than 250 Not to be specified

Up to 10 20XXVIIIOver 10 to 45 30

3.0D+80 0.33L38

XXVIIIa Up to 40 0.7a but not more than 15 Not more than 250 Not to be specified 38a

Notes:1. D - diameter of mandrel; lIII - maximum width of the weld.2. Total length of the specimens of types XXVI, XXVII and XXVIII - is assumed to be not less than the indicated value.3. The shape of the specimen cross-section must be the same all over the entire length.


GOST 6996-66

9.3. The test of specimens of types XXVI and XXVIa shall beaccomplished as indicated in Dwg. 39, types XXVIIa and XXVIII - in Dwg. 40,type XXVIIIa - in Dwg. 40a. Distance K between the supports (Dwg. 40) shall beequal to: for specimens of type XXVII - 2.5D, for specimens of type XXVIIa -D+3a, for specimens of type XXVIII - 3D. The distance for specimens of typesXXVI and XXVIa is indicated in Dwg. 39 and for type XXIIIa - in Dwg. 40a.

Smooth increase of the load on the specimen is an obligatory conditionin accomplishing the test. The test is to be run at a rate of not more than 15mm/min on the testing machines or the presses using the supporting rollers.

Mandrel diameter D can vary depending on the steel grade, platethickness, method of heat treatment and should be specified in the respectivestandard technical documentation. If not specified, the diameter of the mandrelis assumed to be equal to two thicknesses of the parent metal. Radius ofcurvature of the support r for the specimens of types XXVI, XXVIa, XXVII andXXVIIa is chosen according to Table 15. For specimens of type XXVIII radius requals 25 mm. For specimens of type XXVIIIa the redius is not specified.

Dwg. 39 Dwg. 40

If the assigned bend angle exceeds 150 o, then after the bending asshown in the diagram given in Dwgs 39, 40, 40a, the bend can be continuedbetween two parallel pressure plates. A spacer having thickness d equal to themandrel diameter is to installed between the specimen ends (Dwg. 41).

Dwg. 40a Dwg. 41

GOST 6996-66

After removal of the spacer the test shall be continued until the sides come incontact.

Table 15

mm

a r

Up to 2Over 2 up to 4Over 4 up to 8Over 8 up to 10Over 10 up to 26Over 26

248

102025


9.4. According to the requirement specified in the standards or othertechnical documentation for the butt one-sided welds, the surface widest or rootsection of the weld is arranged in the tension zone. If not specified, the weldsurface shall be located in the tension zone.

If not otherwise specified in the standards or other technicaldocumentation, then for all types of specimens, except for XXVIIIa, with thetwo-sided butt welds, the weld which was made the second should be arrangedin the tension zone. For the specimens of type XXVIIIa the entire cross sectionof the weld falls into the tension zone. In welding multilayer two-sided buttwelds with transverse application of passes the side on which the last pass wasaccomplished must be arranged in the tension zone.

The joints having the back bead are treated as one-sided joints.


9.5. The bend testing of the pipe butt joints with transverse (circular)location of the weld is accomplished on the specimens with the increasedthickness removed from the outer side.

For the pipe diameter ≤20 mm use is made of the specimens in the formof the pipe lengths.

If the pipe diameter is more than 20 to 45 mm, use is made of thespecimens in the form of the pipe lengths or flat (segmental) specimens.

If the pipe diameter is more than 45 mm, then flat (segmental)specimens should be used of types XXVII, XXVIIa and XXVIII - theirdimensions are indicated in Table 14. The specimens need not to bestraightened. Their shape in the cross-section is determined by the pipe naturalcurvature.

GOST 6996-66

The testing of the pipes 60 mm in diameter and less with the transverse(circular) and longitudinal welds can be made on specimens given in Dwg. 42 or43.

The increased thickness of the weld is removed from the pipe outer sidemechanically to the level of the parent metal.

Type XXIX Type XXX

Dwg. 42 Dwg. 43

On the specimens cut from the pipes accomplished by resistance buttwelding, the fin must be removed from the outer and inner sides of the pipe tothe level of the parent metal.


9.6. The results of testing specimens of types XXIX and XXX aredetermined by value b (Dwg. 44) when a crack appears on the specimensurface. The characteristic of the crack shall correspond to that indicated initem 9.1.

If the crack is not formed, the test must be continued until the sidescome in contact.

Dwg. 44 Dwg. 45

(Revised version, Amendment No.2 and No. 3).

GOST 6996-66

9.7. The test shall be accomplished by deforming the specimen bypressing with the compressive load.

Smooth increase of the force on the specimen is an obligatory conditionin accomlishing the test. The test rate shall correspond to that indicated in item9.3.

In testing the specimens with the circular weld the latter must be locatedalong the axis of compressive load application (Dwg. 45) and in testing thespecimen with the longitudinal weld, the weld shall must be located in thediametral plane perpendicular to the compressive load action (Ref. Dwg. 44).

If the specimen intended for the test of the circular weld has alongitudinal weld, the lather must be located outside the tension zone.

9.8. The joints of the bars having circular or polyhedral section in theabsence of the standard technical documents must be tested on the followingspecimens:

with the bar diameter or the diameter of the circumference inscribed inthe polyhedral section ≤20 mm, the lengths of the real joint with the removedincreased thickness must be tested;

with the bar diameter or the diameter of the inscribed circumferenceexceeding 20 to 50 mm, the lengths of the real joint with the removed increasedthickness or flat specimens of type XXVIIa must be tested whose thickness isassumed to be equal to half the diameter of the round bar or the circumferenceinscribed in the section of the polyhedral bar;

with the bar diameter or the diameter of the circumference inscribed inthe section of the polyhedron exceeding 50 mm, the flat specimens of typeXXVIIa are tested, whose parent metal thickness is assumed to be equal to halfthe diameter of the round bar or the circumference inscribed in the polyhedronsection.

In all cases the working length of the specimen must be ≥250 mm andthe radius of curvature of the polyhedron edges equals 0.1 of the specimenthickness, but not more than 2 mm.

(Introduced additionally, Amendment No. 2 and No. 3)

10. IMPACT BREAK TEST OF THE WELDED JOINT

10.1. Impact break resistance test is run for the butt welded joints of thesheets up to 2 mm thick.

10.2. The shape and the dimensions of the specimen should correspondto Dwg. 46. In testing high-strength materials it is permissible to change thedesign of the specimen gripping portion.

GOST 6996-66

Type XXXI


10.3. The test is perfromed on the pendulum impact testing machineswith the appliance for attachment of flat specimens. The specific impact work isdetermined from the formula:

aу = Aу/V,

where Aу - impact work spent for breaking the specimen, J (kgf.m);V - volume of the design portion of the specimen equal to the productof the parent metal thickness (a) by the design length and width of thespecimen, cm3 (m3).

GOST 6996-66

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Academy of Sciences of theUSSRDEVELOPERS

A.A. Kazimirov, I.I. Zyubin, S.A. Ostrovskaya

2. APPROVED AND PUT INTO EFFECT by Resolution of the Committeefor standards, measures and instrumentation at the Soviet of Ministers ofthe USSR on 03.03.66 No. 4736

3. SUPERSEDES GOST 6996-54

4. The standard fully complies with CT CЭВ 3521-82 - СT CЭВ 3524-82,СT CЭВ 6732-89

5. REFERENCE STANDARD TECHNICAL DOCUMENTS

Designation of reference standardtechnical document

Item No.

GOST 1497-84GOST 2999-75GOST 9012-59GOST 9013-59GOST 9454-78GOST 9651-84GOST 11150-84

3.6, 4.4, 8.2, 8.4, 8.7, 8.8, 8.93.6, 7.23.6, 7.23.6, 7.23.63.6, 4.53.6

6. Reprint (May, 1991) with Amendments Nos 1, 2, 3, approved in June1980, September 1983, December 1990 (IUS 8-80, 1 - 84, 5 - 91)

gost 6996-66

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