manual técnico de parafusos - bossard
DESCRIPTION
A bíblia das juntas parafusadas :)TRANSCRIPT
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Technical information
Technical information
T.000
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Technical information
frompage
Materials screws & nuts T.002Definitions of mechanical properties for screws T.002
Screws Property class 4.6 to 12.9/12.9 T.004
NutsProperty class 04 to 12 T.009
Set screws Property class 14 H to 45 H T.012
Screws, bolts, nuts T.013
Screws and nutsfor high and low temperatures T.016
Stainless steel fasteners T.020
Fasteners of various materials T.026
Corrosion protection T.031
Arrangement, design, assembly T.034
Selection of fasteners T.034
Fatigue resistance T.035
Length of engaged thread T.036
Surface pressure when mounted T.037
Friction and friction coefficients T.041
Tightening method, tightening factor A T.042
Preload and tightening torques T.044
Securely fastened connections T.055
Shear loads for pins T.058
Construction recommendations T.059
Assembly tools T.072
frompage
Metric ISO threads T.074
Tolerances, tables, standards T.077
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Materials screws & nuts
Definitions of mechanical properties for screws
Definitions of mechanical properties for screws
Tensile strength Rm [N/mm2]Determines how much stress a screw must withstand without breaking. If full size screws are tested, the yield strengthcan only be approximately established. Under ISO 898 Part 1, the exact yield strength and elongation after fracture can be deter-mined using machined specimens. Exceptions are stainlesssteel screws A1 to A4 (ISO 3506).
Tensile strength at rupture in thread:
Rm = max. tensile force F N stress area mm2
Tensile strength at rupture in cylindrical shank:
Rm = max. tensile force F Ninitial cross section of specimen mm2
F
Tensile test onfull size screw
Yield strength ReL [N/mm2]Yield strength is the amount of resistance of a material to plastic deformation. In general terms, yield strength determines how much stress a screw (specimen) must withstand without being permanently elongated. This applies to relatively soft materials.
elongation
tens
ile fo
rce
max
. ten
sile fo
rce
yield po
int
0,2 % limit Rp0,2 [N/mm2]The yield point of somewhat harder materials is not sharply pro-nounced. It is then replaced by the stress at which the permanent elongation is 0.2 %.In practice, screws may be stressed by tightening and underwork-ing load no more than up to the yield strength or the 0,2 limit.
elongation
tens
ile fo
rce
max
. ten
sile fo
rce
limit R
p0,2
Tensile teston machinedscrew
Stress area As [mm2] of thread Pages T.038, T.039
1 N/mm2 = 1 MPa = 145.03 psi
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Elongation at fracture A [%]is the permanent elongation measured on the fractured specimen related to the original measured length. Exceptions: screws A1 to A4, where this is measured on fullsize screws (ISO 3506).
do
Lo = 5 x do
measuring length
Tensile strength under wedge loadingIs tested by means of having a wedge positioned underneath the screw head. When tensioned, the screw must break in the thread or in the shank. Bolts and screws are subjected to a wedge test to measure the ductility and head integrity.
Head soundnessThe head of the screw must withstand several hammer blows. After being bent to a specified angle, the shank head fillet shall not show any signs of cracking. For details see ISO 898, part 1.
Notch Impact Strength [Joule] ISO 83Notch impact energy is the impact energy consumed duringnotch impact testing. A notched sample is taken from the screwnear the surface. This sample is broken in a pendulum impact tester with a single stroke. It gives information on micro-structure, steel making process, inclusion content etc. The values cannot be used for calculations.
Surface FlawsSurface defects arising in the semi-finished product are slag inclusions, material folds and die marks. Cracks on the other hand are crystalline breaks without inclusion of foreign materials. For details see EN 493 and ISO 6157.
DecarburizationDecarburization is a loss of carbon at the surface of ferrous materials (steels). For details see ISO 898, part 1.
F
Materials screws & nuts
Definitions of mechanical properties for screws
HardnessHardness is generally the resistance of the material to penetration by a test body. The advantage of the Vickers hardness test is that the entire hardness range encountered in the screw is covered by the method. For details see ISO 898, part 1.
Vickers hardness HV: ISO 6507Test body-pyramid(encompasses the complete hardness range usual for screws)
Brinell hardness HB: ISO 6506 Test body ball
Rockwell hardness HRC: ISO 6508Test body cone
Hardness comparison tables Page T.082
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Materials screws & nuts
Screws Property class 4.6 to 12.9/12.9
Mechanical and physical properties of screws
according to ISO 898, part 1
The mechanical properties are given for tests at room temperature.
No. Mechanical or physical property Property class4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9/
12.9d 16 d > 16 d 16mm a mm b mm
1 Tensile strength, Rm, MPa, [N/mm2] nom.c 400 400 500 500 600 800 800 900 1 000 1 200
min. 400 420 500 520 600 800 830 900 1 040 1 2202 Lower yield strength, ReLd, MPa, [N/mm2] nom.c 240 300
min. 240 300 3 Stress at 0,2 % non-proportional elongation
Rp0,2, MPa, [N/mm2]nom.c 640 640 720 900 1080min. 640 660 720 940 1 100
4 Stress at 0,0048 d non-proportional elongationfor full-size fasteners Rpf, MPa, [N/mm
2]nom.c 320 400 480 min. 340e 420e 480e
5 Stress under proof load, Spf, MPa, [N/mm2] nom. 225 310 280 380 440 580 600 650 830 970
Proof strength ratio
Sp, nom/ReL min or 0,94 0,91 0,93 0,90 0,92 0,91 0,91 0,90 0,88 0,88Sp, nom/Rp0,2 min orSp, nom/Rpf min
6 Percentage elongation after fracture for machinedtest pieces, A, %
min. 22 20 12 12 10 9 8
7 Percentage reduction of area afterfracture for machined test pieces, Z, %
min. 52 52 48 48 44
8 Elongation after fracture for full-size fasteners, Af(see also ISO 898-1 Annex C)
min. 0,24 0,22 0,20
9 Head soundness no fracture10 Vickers hardness, HV
F 98 Nmin. 120 130 155 160 190 250 255 290 320 385max. 220g 220g 220g 220g 250 320 335 360 380 435
11 Brinell hardness, HBWF = 30 D2
min. 114 124 147 152 181 238 242 276 304 366max. 209g 209g 209g 209g 238 304 318 342 361 414
12 Rockwell hardness, HRB min. 67 71 79 82 89 max. 95,0g 95,0g 95,0g 95,0g 99,5
Rockwell hardness, HRC min. 22 23 28 32 39max. 32 34 37 39 44
13 Surface hardness, HV 0,3 max. h h h h, i h, j14 Height of non-decarburized thread zone,
E, mmmin. 1/2 H1 1/2 H1 1/2 H1 2/3 H1 3/4 H1
Depth of complete decarburization in the thread, G, mm
max. 0,015 0,015 0,015 0,015 0,015
15 Reduction of hardness after retempering, HV max. 20 20 20 20 2016 Breaking torque, MB Nm min. in accordance with ISO 898-717 Impact strength Kvk, l, J min. 27 27 27 27 27 m
18 Surface integrity in accordance withISO 6157-1n ISO
6157-3
a Values do not apply for structural bolting.b For structural bolting d M12.c Nominal values are specified only for the purpose of the desigation system for property classes. See clause 5.d In cases where the lower yield strength ReL cannot be determined, it is permissible to measure the stress at 0,2 % non-proportional elongation Rp0,2.e For the property classes 4.8, 5.8 and 6.8 the values for Rpf min are under investigation. The present values are given for calculation of the proof stress ratio
only. They are not test values.f Proof loads are specified in tables T.006.g Hardness determined at the end of a fastener shall be 250 HV, 238 HB or 99,5 HRB maximum.h Surface hardness shall not be more than 30 Vickers points above the measured core hardness of the fastener when determination of both surface hardness
and core hardness are carried out with HV 0,3.i Any increase in hardness at the surface which indicates that the surface hardness exceeds 390 HV is not acceptable.j Any increase in hardness at the surface which indicates that the surface hardness exceeds 435 HV is not acceptable.k Values are determined at a test temperature of 20 C.l Applies to d 16 mm.m Value for KV is under investigation.n Instead of ISO 6157-1, ISO 6157-3 may apply by agreement between the manufacturer and the purchaser.
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Screws Property class 4.6 to 12.9/12.9
Minimum ultimate tensile loads
according to ISO 898, part 1
Minimum ultimate tensile loads ISO metric coarse pitch thread
Thread1)
dNominalstress areaAs, nom[mm2 ]
Minimum ultimate tensile load Fm min (As, nom x Rm, min) [ N ] Property class
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9/12.9
M3 5,03 2 010 2 110 2 510 2 620 3 020 4 020 4 530 5 230 6 140M3,5 6,78 2 710 2 850 3 390 3 530 4 070 5 420 6 100 7 050 8 270M4 8,78 3 510 3 690 4 390 4 570 5 270 7 020 7 900 9 130 10 700M5 14,2 5 680 5 960 7 100 7 380 8 520 11 350 12 800 14 800 17 300M6 20,1 8 040 8 440 10 000 10 400 12 100 16 100 18 100 20 900 24 500M7 28,9 11 600 12 100 14 400 15 000 17 300 23 100 26 000 30 100 35 300M8 36,6 14 6002) 15 400 18 3002) 19 000 22 000 29 2002) 32 900 38 1002) 44 600M10 58,0 23 2002) 24 400 29 0002) 30 200 34 800 46 4002) 52 200 60 3002) 70 800M12 84,3 33 700 35 400 42 200 43 800 50 600 67 4003) 75 900 87 700 103 000M14 115 46 000 48 300 57 500 59 800 69 000 92 0003) 104 000 120 000 140 000M16 157 62 800 65 900 78 500 81 600 94 000 125 0003) 141 000 163 000 192 000M18 192 76 800 80 600 96 000 99 800 115 000 159 000 200 000 234 000M20 245 98 000 103 000 122 000 127 000 147 000 203 000 255 000 299 000M22 303 121 000 127 000 152 000 158 000 182 000 252 000 315 000 370 000M24 353 141 000 148 000 176 000 184 000 212 000 293 000 367 000 431 000M27 459 184 000 193 000 230 000 239 000 275 000 381 000 477 000 560 000M30 561 224 000 236 000 280 000 292 000 337 000 466 000 583 000 684 000M33 694 278 000 292 000 347 000 361 000 416 000 576 000 722 000 847 000M36 817 327 000 343 000 408 000 425 000 490 000 678 000 850 000 997 000M39 976 390 000 410 000 488 000 508 000 586 000 810 000 1 020 000 1 200 000
1) Where no thread pitch is indicated in a thread designation, coarse pitch is specified.2) For fasteners with thread tolerance 6az according to ISO 965-4 subject to hot dip galvanizing, reduced values in accordance with ISO 10684.3) For structural bolting 70 000 N (for M12), 95 500 N (for M14) and 130 000 N (for M16).
Minimum ultimate tensile loads ISO metric fine pitch thread
Threadd x P
Nominalstress areaAs, nom[mm2 ]
Minimum ultimate tensile load Fm min (As, nom x Rm, min) [ N ]Property class
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9/12.9
M8 x 1 39,2 15 700 16 500 19 600 20 400 23 500 31 360 35 300 40 800 47 800M10 x 1 64,5 25 800 27 100 32 300 33 500 38 700 51 600 58 100 67 100 78 700M10 x 1,25 61,2 24 500 25 700 30 600 31 800 36 700 49 000 55 100 63 600 74 700M12 x 1,25 92,1 36 800 38 700 46 100 47 900 55 300 73 700 82 900 95 800 112 000M12 x 1,5 88,1 35 200 37 000 44 100 45 800 52 900 70 500 79 300 91 600 107 000M14 x 1,5 125 50 000 52 500 62 500 65 000 75 000 100 000 112 000 130 000 152 000M16 x 1,5 167 66 800 70 100 83 500 86 800 100 000 134 000 150 000 174 000 204 000M18 x 1,5 216 86 400 90 700 108 000 112 000 130 000 179 000 225 000 264 000M20 x 1,5 272 109 000 114 000 136 000 141 000 163 000 226 000 283 000 332 000M22 x 1,5 333 133 000 140 000 166 000 173 000 200 000 276 000 346 000 406 000M24 x 2 384 154 000 161 000 192 000 200 000 230 000 319 000 399 000 469 000M27 x 2 496 198 000 208 000 248 000 258 000 298 000 412 000 516 000 605 000M30 x 2 621 248 000 261 000 310 000 323 000 373 000 515 000 646 000 758 000M33 x 2 761 304 000 320 000 380 000 396 000 457 000 632 000 791 000 928 000M36 x 3 865 346 000 363 000 432 000 450 000 519 000 718 000 900 000 1 055 000M39 x 3 1 030 412 000 433 000 515 000 536 000 618 000 855 000 1 070 000 1 260 000
To calculate the nominal stress area As, nom Page T.038
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Proof loads of screws
according to ISO 898, part 1
Proof loads ISO metric coarse pitch thread
Thread1)
dNominalstress areaAs, nom [ mm2 ]
Proof load Fp (As, nom x Sp, nom) [ N ]
Property class
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9/12.9
M3 5,03 1 130 1 560 1 410 1 910 2 210 2 920 3 270 4 180 4 880M3,5 6,78 1 530 2 100 1 900 2 580 2 980 3 940 4 410 5 630 6 580M4 8,78 1 980 2 720 2 460 3 340 3 860 5 100 5 710 7 290 8 520M5 14,2 3 200 4 400 3 980 5 400 6 250 8 230 9 230 11 800 13 800M6 20,1 4 520 6 230 5 630 7 640 8 840 11 600 13 100 16 700 19 500M7 28,9 6 500 8 960 8 090 11 000 12 700 16 800 18 800 24 000 28 000M8 36,6 8 2402) 11 400 10 2002) 13 900 16 100 21 2002) 23 800 30 4002) 35 500M10 58,0 13 0002) 18 000 16 2002) 22 000 25 500 33 7002) 37 700 48 1002) 56 300M12 84,3 19 000 26 100 23 600 32 000 37 100 48 9003) 54 800 70 000 81 800M14 115 25 900 35 600 32 200 43 700 50 600 66 7003) 74 800 95 500 112 000M16 157 35 300 48 700 44 000 59 700 69 100 91 0003) 102 000 130 000 152 000M18 192 43 200 59 500 53 800 73 000 84 500 115 000 159 000 186 000M20 245 55 100 76 000 68 600 93 100 108 000 147 000 203 000 238 000M22 303 68 200 93 900 84 800 115 000 133 000 182 000 252 000 294 000M24 353 79 400 109 000 98 800 134 000 155 000 212 000 293 000 342 000M27 459 103 000 142 000 128 000 174 000 202 000 275 000 381 000 445 000M30 561 126 000 174 000 157 000 213 000 247 000 337 000 466 000 544 000M33 694 156 000 215 000 194 000 264 000 305 000 416 000 576 000 673 000M36 817 184 000 253 000 229 000 310 000 359 000 490 000 678 000 792 000M39 976 220 000 303 000 273 000 371 000 429 000 586 000 810 000 947 000
1) Where no thread pitch is indicated in a thread designation, coarse pitch is specified.2) For fasteners with thread tolerance 6az according to ISO 965-4 subject to hot dip galvanizing, reduced values in accordance with ISO 10684.3) For structural bolting 50 700 N (for M12), 68 800 N (for M14) and 94 500 N (for M16).
Proof loads ISO metric fine pitch thread
Thread d x P
Nominalstress areaAs, nom[ mm2 ]
Proof load Fp (As, nom x Sp, nom) [ N ]
Property class
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9/12.9
M8 x 1 39,2 8 820 12 200 11 000 14 900 17 200 22 700 25 500 32 500 38 000M10 x 1,25 61,2 13 800 19 000 17 100 23 300 26 900 35 500 39 800 50 800 59 400M10 x 1 64,5 14 500 20 000 18 100 24 500 28 400 37 400 41 900 53 500 62 700M12 x 1,25 92,1 20 700 28 600 25 800 35 000 40 500 53 400 59 900 76 400 89 300M12 x 1,5 88,1 19 800 27 300 24 700 33 500 38 800 51 100 57 300 73 100 85 500M14 x 1,5 125 28 100 38 800 35 000 47 500 55 000 72 500 81 200 104 000 121 000M16 x 1,5 167 37 600 51 800 46 800 63 500 73 500 96 900 109 000 139 000 162 000M18 x 1,5 216 48 600 67 000 60 500 82 100 95 000 130 000 179 000 210 000M20 x 1,5 272 61 200 84 300 76 200 103 000 120 000 163 000 226 000 264 000M22 x 1,5 333 74 900 103 000 93 200 126 000 146 000 200 000 276 000 323 000M24 x 2 384 86 400 119 000 108 000 146 000 169 000 230 000 319 000 372 000M27 x 2 496 112 000 154 000 139 000 188 000 218 000 298 000 412 000 481 000M30 x 2 621 140 000 192 000 174 000 236 000 273 000 373 000 515 000 602 000M33 x 2 761 171 000 236 000 213 000 289 000 335 000 457 000 632 000 738 000M36 x 3 865 195 000 268 000 242 000 329 000 381 000 519 000 718 000 839 000M39 x 3 1 030 232 000 319 000 288 000 391 000 453 000 618 000 855 000 999 000
To calculate the nominal stress area As, nom Page T.038
Materials screws & nuts
Screws Property class 4.6 to 12.9/12.9
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Materials, heat treatment, chemical compositions
according to ISO 898, part 1
Steels
Propertyclass
Material and heat treatment Chemical composition limits (cast analysis, %)1)
Temperingtemperature
C P S B2) C
min. max. max. max. max. min.
4.63), 4) Carbon steel or carbon steel with additives 0,55 0,05 0,06 not specified
4.84)
5.63) 0,13 0,55 0,05 0,06
5.84) 0,55 0,05 0,066.84) 0,15 0,55 0,05 0,06
8.86) Carbon steel with additives (e.g. Boron or Mn or Cr), quenched and tempered
0,155) 0,40 0,025 0,025 0,003 425
or 0,25 0,55 0,025 0,025Carbon steel, quenched and tempered
or 0,20 0,55 0,025 0,025Alloyed steel, quenched and tempered7)
9.86) Carbon steel with additives (e.g. Boron or Mn or Cr), quenched and tempered
0,155) 0,40 0,025 0,025 0,003 425
or 0,25 0,55 0,025 0,025Carbon steel, quenched and tempered
or 0,20 0,55 0,025 0,025Alloyed steel, quenched and tempered7)
10.96) Carbon steel with additives (e.g. Boron, Mn or Cr), quenched and tempered
0,205) 0,55 0,025 0,025 0,003 425
or 0,25 0,55 0,025 0,025Carbon steel, quenched and tempered
or 0,20 0,55 0,025 0,025Alloyed steel, quenched and tempered7)
12.96), 8), 9) Alloyed steel, quenched and tempered7) 0,30 0,50 0,025 0,025 0,003 425
12.96), 8), 9) Carbon steel with additives (e.g. Boron, Mn or Cr or Molybdenum), quenched and tempered
0,28 0,50 0,025 0,025 0,003 380
1) In case of dispute, the product analysis applies. 2) Boron content can reach 0,005 %, provided that non-effective boron is controlled by addition of titanium and/or aluminium.3) For cold forged fasteners of property classes 4.6 and 5.6, heat treatment of the wire used for cold forging or of the cold forged fastener itself may be
necessary to achieve required ductility.4) Free cutting steel is allowed for these property classes with the following maximum sulphur, phosphorus and lead contents: sulphur 0,34 %; phosphorus
0,11 %; lead 0,35 %.5) In case of plain carbon boron steel with a carbon content below 0,25 % (cast analysis), the minimum manganese content shall be 0,6 % for property class 8.8
and 0,7 % for 9.8 and 10.9.6) For the materials of these property classes, there shall be a sufficient hardenabiltity to ensure a structure consisting of approximately 90 % martensite in the
core of the threaded sections for the fasteners in the "as-hardened" condition before tempering.7) This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0,3 %, nickel 0,3 %, molybdenum 0,2 %,
vanadium 0,1 %. Where elements are specified in combinations of two, three or four and have alloy contents less than those given above, the limit value to be applied for class determination is 70 % of the sum of the individual limit values shown above for the two, three or four elements concerned.
8) A metallographically detectable white phosphorous enriched layer is not permitted for property class 12.9/12.9. It shall be detected by a suitable test method.9) Caution is advised when the use of property class 12.9/12.9 is considered. The capability of the fastener manufacturer, the service conditions and the
wrenching methods should be considered. Environments may cause stress corrosion cracking of fasterners as processed as well as those coated.
Materials screws & nuts
Screws Property class 4.6 to 12.9/12.9
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Influence of elevated temperatures on mechanical properties of fasteners Elevated temperatures can cause changes in the mechanical properties and in the functional performance of a fastener.
Up to typical service temperatures of 150 C, no detrimental effects due to a change of mechanical properties of fasteners are known. At temperatures over 150 C and up to a maximum temperature of 300 C, the functional performance of fasteners should be ensured by careful examination.
With encreasing temperatures, a progressive reduction of lower yield strength or stress at 0,2 % non-propor-tional elongation or stress at 0,0048 d non-proportional elongation for finished fasteners, and reduction of tensile strength can be experienced. The continu-ous operating of fasteners at elevated service temperatures can result in stress relaxation, which increases with higher tempera-tures. Stress relaxation accompanies a loss of clamp force.
Work-hardened fasteners (property classes 4.8, 5.8, 6.8) are more sensitive with regard to stress relaxation compared with quenched and tempered or stress-relieved fasteners.
Care should be taken when lead-containing steels are used for fasteners at elevated temperatures. For such fasteners, a risk of liquid metal embrittlement (LME) should be taken into consider-ation when the service temperature is in the range of the melting point of lead.
Information for example, in EN 10269 and in ASTM F2281.
Influence of higher screw property class under comprehension of the mechanical stress and environmental conditions.
High-strength material
Brittling of material stress corrosion cracking hydrogen embrittlement
Mechanical fracture forced fracture fatigue fracture shear fracture cleavage fracture mixed fracture oscillating fracture
Erosion corrosion uniform corrosion pitting corrosion crevice corrosion galvanic corrosion
Ambient medium e.g. hydrogen, acid rain
Mechanical stress
Risk of hydrogen embrittlement Page T.031
Characteristics at elevated temperatures
according to ISO 898, part 1
Characteristics at higher strength (if 1000 N/mm2)
Materials screws & nuts
Screws Property class 4.6 to 12.9/12.9
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Mechanical properties of nuts with ISO metric threads (coarse)
according to ISO 898, part 2
Property class
Thread-to M4 > M4 to M7 > M7 to M10 > M10 to M16 > M16 to M39
04 Stress under proof load, Sp, [N/mm2] 380 380 380 380 380Vickers hardness HV min. 188 188 188 188 188
max. 302 302 302 302 30205 Stress under proof load, Sp, [N/mm2] 500 500 500 500 500
Vickers hardness HV min. 272 272 272 272 272max. 353 353 353 353 353
4 Stress under proof load, Sp, [N/mm2] 510Vickers hardness HV min. 117
max. 3025 Stress under proof load, Sp, [N/mm2] 520 580 590 610 630
Vickers hardness HV min. 130 130 130 130 146max. 302 302 302 302 302
6 Stress under proof load, Sp, [N/mm2] 600 670 680 700 720Vickers hardness HV min. 150 150 150 150 170
max. 302 302 302 302 30283) Stress under proof load, Sp, [N/mm2] 800 855 870 880 920
Vickers hardness HV min. 180 200 200 200 233max. 302 302 302 302 353
9 Stress under proof load, Sp, [N/mm2] 900 915 940 950 920Vickers hardness HV min. 170 188 188 188 188
max. 302 302 302 302 30210 Stress under proof load, Sp, [N/mm2] 1 040 1 040 1 040 1 050 1 060
Vickers hardness HV min. 272 272 272 272 272max. 353 353 353 353 353
121) Stress under proof load, Sp, [N/mm2] 1 140 1 140 1 140 1 170 Vickers hardness HV min. 295 295 295 295
max. 353 353 353 353 122) Stress under proof load, Sp, [N/mm2] 1 150 1 150 1 160 1 190 1 200
Vickers hardness HV min. 272 272 272 272 272max. 353 353 353 353 353
1) Nuts style 1 (ISO 4032) 0,9 d nuts2) Nuts style 2 (ISO 4033) 1,0 d nuts3) Class 8 M16 only type 1 (not heat-treated) > M16 type 1 (hardened and tempered) and type 2 (not heat-treated)
Property class Nuts Thread
05 to 8 Type1 metric ISO thread > M16
05 to 8 Type1 fine pitch thread
10 and 12 metric ISO thread fine pitch thread
The mechanical properties as listed apply to heat-treated nuts: Notes The minimum hardness values are binding only for nuts for
which a test stress measurement can not be performed and for heat treated nuts. The minimum values are guidelines for all other nuts.
The minimum hardness values for nuts with nominal thread diameters above 39 and to 100 mm are for information only and are considered reference values.
Materials screws & nuts
Nuts Property classes 04 to 12
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Materials screws & nuts
Nuts Property classes 04 to 12
The standard values for strip resistance relate to the given bolt classes. The exterior thread may be expected to strip if the nuts are paired with screws of lower property classes, while the thread of the nut will strip if it is paired with screws of higher property classes.
Propertyclass of nut
Proof loadstressof the nut[N/mm2]
Minimum stress in the core of bolt when stripping occurs for bolts with property class
[N/mm2]6.8 8.8 10.9 12.9
04 380 260 300 330 35005 500 290 370 410 480
Thread1) Nominal stress area of thematerial AS [mm2 ]
Test load (AS x Sp), [ N ]
Property class
04 05 4 5 6 8 9 10 12
Style 1 Style 1 Style 1 Style 1 Style 2 Style 2 Style 2 Style 2 Style 2M3 5,03 1 910 2 500 2 600 3 000 4 000 4 500 5 200 5 700 5 800M3,5 6,78 2 580 3 400 3 550 4 050 5 400 6 100 7 050 7 700 7 800M4 8,78 3 340 4 400 4 550 5 250 7 000 7 900 9 150 10 000 10 100M5 14,2 5 400 7 100 8 250 9 500 12 140 13 000 14 800 16 200 16 300M6 20,1 7 640 10 000 11 700 13 500 17 200 18 400 20 900 22 900 23 100M7 28,9 11 000 14 500 16 800 19 400 24 700 26 400 30 100 32 900 33 200M8 36,6 13 900 18 300 21 600 24 900 31 800 34 400 38 100 41 700 42 500M10 58,0 22 000 29 000 34 200 39 400 50 500 54 500 60 300 66 100 67 300M12 84,3 32 000 42 200 51 400 59 000 74 200 80 100 88 500 98 600 100 300M14 115 43 700 57 500 70 200 80 500 101 200 109 300 120 800 134 600 136 900M16 157 59 700 78 500 95 800 109 900 138 200 149 200 164 900 183 700 186 800M18 192 73 000 96 000 97 900 121 000 138 200 176 600 170 900 176 600 203 500 230 400M20 245 93 100 122 500 125 000 154 000 176 400 225 400 218 100 225 400 259 700 294 000M22 303 115 100 151 500 154 500 190 900 218 200 278 800 269 700 278 800 321 200 363 600M24 353 134 100 176 500 180 000 222 400 254 200 324 800 314 200 324 800 374 200 423 600M27 459 174 400 229 500 234 100 289 200 330 500 422 300 408 500 422 300 486 500 550 800M30 561 213 200 280 500 286 100 353 400 403 900 516 100 499 300 516 100 594 700 673 200M33 694 263 700 347 000 353 900 437 200 499 700 638 500 617 700 638 500 735 600 832 800M36 817 310 500 408 500 416 700 514 700 588 200 751 600 727 100 751 600 866 000 980 400M39 976 370 900 488 000 497 800 614 900 702 700 897 900 868 600 897 900 1 035 000 1 171 000
1) If the description of the thread does not include thread pitch then the reference is to coarse threads (see ISO 261 and ISO 262).
Designation system and stress under proof load for nuts with height 0,5 d, but < 0,8 d
according to ISO 898, part 2
Test loads for nuts
according to ISO 898, part 2
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Nuts with test loads above 350 000 N (values highlighted in blue) can be excluded from a test load trial. The buyer and the manufacturer must agree minimum hardnesses for these particular nuts.
Thread1) Nominal stress area of thematerial AS [mm2 ]
Test load (AS x Sp), [ N ]Property class (code number)
4 5 6 8 10 12
M3 5,03 2 500 3 000 4 000 5 000 6 000M3,5 6,78 3 400 4 050 5 400 6 800 8 150M4 8,78 4 400 5 250 7 000 8 750 10 500M5 14,2 7 100 8 500 11 400 14 200 17 000M6 20,1 10 000 12 000 16 000 20 000 24 000M7 28,9 14 500 17 300 23 000 29 000 34 700M8 36,6 18 300 22 000 29 000 36 500 43 000M10 58,0 29 000 35 000 46 000 58 000 69 500M12 84,3 42 100 50 500 67 000 84 000 100 000M14 115 57 500 69 000 92 000 115 000 138 000M16 157 78 500 94 000 126 000 157 000 188 000M18 192 76 800 96 000 115 000 154 000 192 000 230 000M20 245 98 000 122 000 147 000 196 000 245 000 294 000M22 303 121 000 151 000 182 000 242 000 303 000 364 000M24 353 141 000 176 000 212 000 282 000 353 000 423 000M27 459 184 000 230 000 276 000 367 000 459 000 550 000M30 561 224 000 280 000 336 000 448 000 561 000 673 000M33 694 277 000 347 000 416 000 555 000 694 000 833 000M36 817 327 000 408 000 490 000 653 000 817 000 980 000M39 976 390 000 488 000 585 000 780 000 976 000 1 170 000
1) If the designation of the thread does not indicate thread pitch then the reference is to coarse threads (see DIN 13).
Property class Chemical composition in terms of % by weight (test analysis)
C Mn P S
max. min. max. max.
41), 51), 61) 0,50 0,060 0,1508, 9 041) 0,58 0,25 0,060 0,150102) 052) 0,58 0,30 0,048 0,058122) 0,58 0,45 0,048 0,058
1) Nuts of these strength classes may be made from free cutting steel, unless other arrangements have been agreed upon between the buyer and the supplier. When using free cutting steel, the following maximum proportions of sulphur, phosphorus and lead are permitted:
sulfur 0,34 % phosphorus 0,11 % lead 0,35 %
2) For these strength classes it may be necessary to add alloys in order to achieve the mechanical properties of the nuts.
Note Nuts of property classes 05, 8 (style 1 above M16 or style 1 fine thread), 10 and 12 must be quenched and tempered.
Test loads for nuts 0,8 d
according to DIN 267, part 4
Chemical compositions of nuts
according to ISO 898, part 2
Materials screws & nuts
Nuts Property classes 04 to 12
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Mechanical properties Property class1)
14 H 22 H 33 H 45 HVickers hardness HV min. 140 220 330 450
max. 290 300 440 560Brinell hardness HB, F = 30 D2
min. 133 209 314 428max. 276 285 418 532
Rockwell hardness HRB min. 75 95 max. 105
Rockwell hardness HRC min. 33 45max. 30 44 53
Surface hardness HV 0,3 max. 320 450 5801) Property class 14 H, 22 H and 33 H are not for hexagon socket set screws
The mechanical properties apply to grub screws and similar, which are not subject to tension and which have threads of diameter from 1,6 to 39 mm, made from unalloyed or alloyed steel. For further details of the mechanical properties of set screws please refer to ISO 898, part 5.
Mechanical properties
according to ISO 898, part 5
Property class Material Heat treatment Chemical compositionin % by weight (random analysis)C P S
min. max. max. max.
14 H High-carbon steel1) 2) 0,50 0,11 0,1522 H High-carbon steel3) quenched and tempered 0,50 0,05 0,0533 H High-carbon steel3) quenched and tempered 0,50 0,05 0,0545 H Alloy steel3) 4) 5) 6) quenched and tempered 0,19 0,50 0,05 0,05
1) Free-cutting steel may be used, with lead content 0,35 % maximum, phosphorus content 0,11 % maximum and sulphur content 0,34 % maximum.2) Case hardening is allowed in the case of square-head set screws.3) Steel with lead content 0,35 % maximum may be used.4) The alloying steel must contain an alloying element or several alloying elements like chromium, nickel, molybdenum, vanadium or bor.5) For thread pins with property class 45H other steels may be used if the conditions of the torque test is conform to ISO 898, part 5. Boron alloyed steels shall
content boron between 0,0008 and 0,005. Hard steel is permitted with min. 0,45 % C if alloying elements contains at least 50 % according to ISO 8981, part 1.6) To M16 boron alloyed carbon steel contents min. 0,35 % C.
Materials, heat treatment and chemical composition
according to ISO 898, part 5
Materials screws & nuts
Set screws Property classes 14 H to 45 H
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Marking symbols Property class
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9 12.9Marking symbols for fasteners with full loadability1)
4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9 12.9
Marking symbols for fasteners with reduced loadability1)
04.6 04.8 05.6 05.8 06.8 08.8 09.8 010.9 012.9 012.9
1) The dot in the marking symbol may be omitted.
Identification with the manufacturers mark and the property class is mandatory for hexagon screws 4.6 to 12.9 and hexagon or hexalobular socket head cap screws 8.8 to 12.9 with thread diameter d 5 mm, where the shape of the screw always allows it. (Marking of bolts and screws are preferably on the head).
ABCD 8.8
8.8
ABCD
Examples of marking on hexagonscrews and bolts.
ABCD 12.9
12.9
ABCD
8.8
XYZ
Examples of marking on hexagon andhexalobular socket head cap screws.
Marking of fasteners
according to ISO 898, part 1
The revised standard as of April 2009 has been for the application for bolts, screws and studs with specified property classes coarse thread and fine pitch thread.
Fasteners according to a product standard with reduced loadabil-ity need to be marked with property class preceded with the digit "0". The objective of the revised head marking is an indicative instruction for the assembly process. The user can further look up for additional notes in the Bossard catalogue. The revised head marking is a defined identification in accordance to the revised standard.
Judgment of the change for the user: Fasteners that are manufactured according to the old
standard have no functional differences compared to the revised standard.
Fasteners according to the mentioned specification are always subjected to reduced loadability due to the head geometry according to ISO 898-1 this means that tightening torques has to be taken into account.
Marking and designation of fasteners with reduced loadability
according to ISO 898, part 1
Materials screws & nuts
Screws, bolts, nuts
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Marking of nuts
according to ISO 898, part 2
Identification with the manufacturer is mark and property class is mandatory for hexagon nuts with thread diameter d 5 mm. The hexagon nuts must be marked with an indentation on the bearing surface or on the side or by embossing on the chamfer. Embossed markings must not protrude beyond the bearing surface of the nut.
AB AB
Example of marking with the codesymbol (clock-face system)
8AB
AB
8
Example of marking with the propertyclass designation
Materials screws & nuts
Screws, bolts, nuts
Marking is obligatory for property classes of or higher than 5.6 and is preferably to be made on the threaded part by an indenta-tion. For adjustment bolts with locking, the marking must be on the side of the nut.Marking is required for bolts of nominal diameter of or greater than 5 mm.
The symbols shown in the table on the right are also authorised as a method of identification.
8.8
XYZ8.8
Marking of studbolts
according to ISO 898, part 1
Property class 5.6 8.8 9.8 10.9 12.9
Marking symbol
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1) Quenched and tempered material
Mating bolts Nuts
Property class Diameter range
Property class Diameter range Type 1 Type 2 Type 0,5 d
3.6 to 12.9reduced loadability
M39 04 < M3905 < M391)
3.6, 4.6, 4.8 > M16 4 > M16 3.6, 4.6, 4.8 M16 5 M16 5.6, 5.8 M39 > M16 M396.8 M39 6 M39 08.8reduced loadability
M39 |8| M16 > M16 M39 > M16 M391)
8.8 M39 8 M16 > M16 M39 > M16 M391)
9.8 M16 9 M16 10.9 M39 10 M391) 12.9 M39 12 M161) M391)
Assignment of possible property classes of screws and nuts
RemarkIn general, nuts of a higher property class are preferable to nuts of a lower property class. This is advisable for a bolt / nut assembly stressed higher than the yield stress or the stress under proof load.
Pairing screws and nuts 0,8 d
according to ISO 898, part 2
|8|
|8|
Groove
Marking of nuts
according to DIN 267, part 4
Property class
Characteristic 4 5 6 8 10 12
Identification mark |4| |5| |6| |8| |10| |12|
Hexagon nuts with nominal thread diameter d 5 mm must be marked with the property class on the bearing surface or on the side. Embossed markings must not protrude beyond the bearing surface of the nut.
For hexagon nuts with nominal thread diameter d 5 mm acc. to DIN 934 and DIN 935 made from free-cutting steel, the marking must also include a groove on one chamfer of the nut (up to property class 6).
Materials screws & nuts
Screws, bolts, nuts
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Mechanical properties min. 0,2 % yield strength values at increased temperatures
according to DIN EN 10269 (old DIN 17240)Material abbreviation Diameter
rangeTensilestrength
Elongationat facture
notch barimpact value
Minimum value for the 0,2 % limit Rp0,2 at [N/mm2] at a temperature [C] of
Materiald Rm Amin KVmin
Name number [mm] [N/mm2] [%] [J] 20 100 200 300 400 500 600hardened and tempered steelsC35E 1.1181 d 60 500 to 650 22 55 300 270 229 192 17335B2 1.5511 d 60 500 to 650 22 55 300 270 229 192 17325CrMo4 1.7218 d 100 600 to 750 18 60 440 428 412 363 304 23542CrMo4 1.7225 d 60 860 to 1060 14 50 730 702 640 562 475 37540CrMoV4-7 1.7711 d 100 850 to 1000 14 30 700 670 631 593 554 470 293X22CrMoV12-1 1.4923 d 160 800 to 950 14 27 600 560 530 480 420 335X19CrMoNbVN11-1 1.4913 d 160 900 to 1050 12 20 750 701 651 627 577 495 305work-hardened austenitic steelsX5CrNi18-10 1.4301 d 35 700 to 850 20 80 350 155 127 110 98 92X5CrNiMo17-12-2 1.4401 d 35 700 to 850 20 80 350 175 145 127 115 110X5NiCrTi26-5 1.4980 d 160 900 to 1150 15 50 600 580 560 540 520 490 430
Material abbreviation Density Static modulus of elasticity E in [kN/mm2]at a temperature [C]
Material
Name number [kg/dm3] 20 100 200 300 400 500 600hardened and tempered steelsC35E 1.1181 7,85 211 204 196 186 177 164 12740CrMoV4-7 1.7711X19CrMoNbVN11-1 1.4913 7,7 216 209 200 190 179 167 127X22 CrMoV12-1 1.4923work-hardened austenitic steelsX5CrNi18-10 1.4301 7,9 200 194 186 179 172 165 X5CrNiMo17-12-2 1.4401 8,0X5NiCrTi26-15 1.4980 8,0 2111) 2061) 2001) 1921) 1831) 1731) 1621)
Typical values for the coefficient of thermal expansion, thermal conductivity and heat capacity
excerpt from DIN EN 10269 (old DIN 17240)
1) Dynamic modulus of elasticity
Material abbreviation Coefficient of thermal expansion in 10-6 / Kbetween 20 C and
Thermal conductivityat 20 C
Specific thermalconductivity at 20 C
MaterialName number 100 C 200 C 300 C 400 C 500 C 600 C [w/(mK)] [J/(kgK)]
hardened and tempered steelsC35E 1.1181 11,1 12,1 12,9 13,5 13,9 14,1 42 46040CrMoV4-7 1.7711 33work-hardened austenitic steelsX5CrNi18-10 1.4301 16,0 16,5 17,0 17,5 18,0 n. a. 15 500X5CrNiMo17-12-2 1.4401X5NiCrTi26-15 1.4980 17,0 17,5 17,7 18,0 18,2 n. a. n. a. n. a.
n. a. = no data available
Typical values for the density and static modulus of elasticity
according to DIN EN 10269 (old DIN 17240)
Materials screws & nuts
Screws and nuts for high and low temperatures
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Material abbreviation
Utilisation temperature limitsName Material number MarkingC35E (N)1) 1.1181 Y +350 CC35E (QT) 1.1181 YK +350 C2)
35B2 1.5511 YB +350 C2)
24CrMo5 1.7258 G +400 C25CrMo4 1.7218 KG +400 C42CrMo4 1.7225 GC +500 C21CrMoV5-7 1.7709 GA +540 C40CrMoV4-6 1.7711 GB +520 CX22CrMoV12-1 1.4923 V3), VH4) +580 CX19CrMoNbVN11-1 1.4913 VW +580 CX7CrNiMoBNb16-16 1.4986 S +650 CX6NiCrTiMoVB25-15-2 1.4980 SD +650 CNiCr20TiAl 2.4952 SB +700 C
1) Applies only to nuts2) For nuts the usual upper bound of the temperature in service may be around 50 C higher.3) Symbol V for material with a 0,2 % proof strength Rp0,2 600 N/mm24) Symbol VH for material with a 0,2 % proof strength Rp0,2 700 N/mm
2
Material abbreviation
Utilisation temperature limitsName Material number Marking Screws25CrMo4 1.7218 KG 60CX12Ni5 1.5680 KB 120 CX5CrNi18-10 1.4301 A21) 200 CX4CrNi18-12 1.4303 A21) 200 CX2CrNi18-9 1.4307 A2L1) 200 CX6CrNiMoTi-17-12-2 1.4571 A51) with head2)
without head2) 60 C200 C
X2CrNi17-12-2 1.4404 A4L1) with head2) 60 Cwithout head2) 200 C
1) The property class must be added to this marking of austenitic steel grades, e.g. A270 Application temperatures down to 200 C for screw property class 70 and 80, nut property class 80. Lower strengths down to 60 C.
2) As a result of the molybdenum content when below the temperature shown these can no longer be expected to have a homogenous austenitic micro-structure.
Material Screw Material NutC35E (QT), 35B2 C35E (N), C35E (QT), 35B225CrMo4, 24CrMo5 C35E (QT), 35B2, 25CrMo421CrMoV5-7 25CrMo4, 21CrMoV5-740CrMoV47, 42CrMo4 21CrMoV5-7, 42CrMo4X22CrMoV12-1 X22CrMoV12-1X19CrMoNbVN11-1 X22CrMoV12-1X7CrNiMoBNb16-16 X7CrNiMoBNb16-16X6NiCrTiMoVB25-15-2 X6NiCrTiMoVB25-15-2NiCr20TiAl NiCr20TiAl
NoteAt the lower limits of the operation temperature indicated in the table, the impact work of notched bar (KV) of the material must be at least 40 Joules.
Table of materials for temperature over +300 C
according to DIN 267, part 13
Materials screws & nuts
Screws and nuts for high and low temperatures
Table of materials for low temperatures from 200 C to 10 C
according to DIN 267, part 13
Pairing materials for screws and nuts
according to DIN 267, part 13
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Temperature [C]
70
60
50
40
30
20
10
0
[%]
-200 -150 -100 -50 0 +20
Necking at rupture KElongation at rupture AImpact strength specimen DVM
DVM [J]200100
0
26 CrMo 4X 12 CRNi 18 9
12 Ni 19X 12 CrNi 18 9X 10 CrNiTi 18 10X 10 CrMoTo 18 10
12 Ni 1926 CrMo4
X 12 CrNi 18 9X 10 CrNiTi 18 1012 Ni 1926 CrMo4
{{
[N/mm2]1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
Temperature [C]
-200 -150 -100 -50 0 +20
26 CrMo 412 Ni 19X 12 CrNi 18 9X 10 CrNiTi 18 1026 CrMo 4 (to -120 C)12 Ni 19
X 12 CrNi 18 9X 10 CrNiTi 18 10
Tensile strength RmYield strength ReL or Rp 0,2
Ductility of steels at low temperatures
according to manufacturers specifications
Yield strength and tensile strength of steels at low temperatures
according to manufacturers specifications
Materials screws & nuts
Screws and nuts for high and low temperatures
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Materials Elastic elongation [mm] prestressed up to approx. 70 % of yield stress at room temperature
L [mm] YK G GA GB V VW S SBE [103 N/mm2] 211 211 211 211 216 216 196 21660 0,056 0,088 0,109 0,139 0,116 0,152 0,107 0,11670 0,065 0,102 0,127 0,162 0,136 0,177 0,125 0,13680 0,074 0,117 0,146 0,186 0,155 0,202 0,143 0,15590 0,084 0,131 0,164 0,209 0,175 0,228 0,161 0,175100 0,093 0,146 0,182 0,232 0,194 0,253 0,179 0,194110 0,102 0,161 0,200 0,255 0,213 0,278 0,197 0,213120 0,112 0,175 0,218 0,278 0,233 0,304 0,215 0,233130 0,121 0,190 0,237 0,302 0,252 0,329 0,233 0,252140 0,130 0,204 0,255 0,325 0,272 0,354 0,251 0,272150 0,140 0,291 0,273 0,348 0,291 0,280 0,269 0,291160 0,149 0,234 0,291 0,371 0,310 0,405 0,286 0,310170 0,158 0,248 0,309 0,394 0,330 0,430 0,304 0,330180 0,167 0,263 0,328 0,418 0,349 0,455 0,322 0,349190 0,177 0,277 0,346 0,441 0,369 0,481 0,340 0,690200 0,186 0,292 0,364 0,464 0,388 0,506 0,358 0,388210 0,195 0,307 0,382 0,487 0,407 0,531 0,376 0,407220 0,205 0,321 0,400 0,510 0,427 0,557 0,394 0,427230 0,214 0,336 0,419 0,534 0,446 0,582 0,412 0,446240 0,223 0,350 0,437 0,557 0,466 0,607 0,430 0,466250 0,233 0,365 0,455 0,580 0,485 0,633 0,448 0,485260 0,242 0,380 0,473 0,603 0,504 0,658 0,465 0,504270 0,251 0,394 0,491 0,626 0,524 0,683 0,483 0,524280 0,260 0,409 0,510 0,650 0,543 0,708 0,501 0,543290 0,270 0,423 0,528 0,673 0,563 0,734 0,519 0,563300 0,279 0,438 0,546 0,696 0,582 0,759 0,537 0,582
Calculation
= [mm]
[mm] = elastic elongation under preload FV
FV [N] = preloadE [N/mm2] = elasticity moduleA [mm2] = cross section area of reduced shankL [mm] = reduced shank length
where:
0,7 = 70 % Rp 0,2
Overview of material Page T.017
L
FV
A
FV
Length of reduced shank
Example
X8CrNiMoBNb16-16 = [S]Rp 0,2 = 500 N/mm2length of reduced shank L = 220 mm
Elastic elongation
= 0,7 500 = 0,394 mm
see table: column S for L = 220 mm
220196000
FVA
FV LE A
Elastic elongation of bolts with reduced shanks
according to DIN 2510
Materials screws & nuts
Screws and nuts for high and low temperatures
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Steel group
F1(C33))
Identification of steelgrades
Screws, nuts type 1
FerriticMartensiticAustenitic
C4A42)A31)A22)A1 A51)
Jam nuts
Property classes
Studs, setscrewsTapping screws
C4C1
soft coldworked
highstrength
soft hardenedand
tempered
soft hardenedand
tempered
hardenedand
tempered
soft coldworked
1) Stabilized against intergranular corrosion through addition of titanum, possibly niobium, tantalum.2) Low carbon austenitic stainless steels with carbon content not exceeding 0,03 % may additionally be marked with an "L", e.g. A4L-80.3) For tapping screws steel grade C3 is used.
Descriptions using a letter/figure combination mean the following:
Abbreviation of composition group:A = austenitic chromium-nickel steel
Abbreviation of chemical composition:1 = free-cutting steel with sulphur additive2 = cold-heading steel alloyed with chromium and nickel3 = cold-heading steel alloyed with chromium and nickel stabilised with Ti, Nb, Ta4 = cold-heading steel alloyed with chromium, nickel and molybdenum5 = cold-heading steel alloyed with chromium, nickel and molybdenum
stabilized with Ti, Nb, Ta
Abbreviation of property class:50 = 1/10 of tensile strength (min. 500 N/mm2)70 = 1/10 of tensile strength (min. 700 N/mm2)80 = 1/10 of tensile strength (min. 800 N/mm2)
A2 70
Thin nuts:025 = proof stress min. 250 N/mm2035 = proof stress min. 350 N/mm2040 = proof stress min. 400 N/mm2
The designation of the steel grade (first block) consists of one of the letters: A for austenitic steel C for martensitic steel F for ferritic steel
Example: A2-70 indicates: austenitic steel, cold worked, min. 700 N/mm2 tensile strength C4-70 indicates: martensitic steel, hardened and tempered, min. 700 N/mm2 tensile
strength The designation of the property class consists of two digits representing 1/10 of the
tensile strength of the fasteners respectively 1/10 of the proof load of the nuts.
If fastener elements are classified over the hardness, the hardness class is given according to Vickers by 2 digits standing for 1/10 ofthe minimum hardness value. The letter H refers to the hardness.
Designation example of a minimum hardness 250 HV: A4 25 H, austenitic steel, cold strengthened
ISO-designated steel groups
according to ISO 3506
Materials screws & nuts
Stainless steel fasteners
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More than 97 % of all fasteners made from stainless steels are produced from this steel composition group. They are character-ised by impressive corrosion resistance and excellent mechanicalproperties.
Steelgroup
Chemical composition in %(maximum values, unless otherwise indicated)
Notes
C Si Mn P S Cr Mo Ni CuA1 0,12 1,0 6,5 0,200 0,150,35 1619 0,7 510 1,752,25 2) 3) 4)
A2 0,10 1,0 2,0 0,050 0,03 1520 819 4 5) 6)A3 0,08 1,0 2,0 0,045 0,03 1719 912 1 1) 7)A4 0,08 1,0 2,0 0,045 0,03 1618,5 23 1015 4 6) 8)
A5 0,08 1,0 2,0 0,045 0,03 1618,5 23 10,514 1 1) 7) 8)
1) Stabilized against intergranular corrosion through addition of titanium, possibly niobium, tantalum.2) Sulfur may be replaced by selenum.3) If the nickel content is below 8 %, the min. manganese content shall be 5 %.4) There is no min. limit to the copper content, provided that the nickel content is greater than 8 %.5) If the chromium content is below 17 %, the min. nickel content should be 12 %.6) For austenitic stainless steels having a max. carbon content of 0,03 %, nitrogen may be present to a max. of 0,22 %.7) This shall contain titanium 5 x C up to 0,8 % max. for stabilization and be marked appropriately as specified in this table, or shall
contain niobium (columbium) and/or tantalum 10 x C up to 1 % maximum for stabilization and be marked approprately as specified in this table.
8) At the discretion of the manufacturer, the carbon content may be higher where required in order to obtain the specified mechanical properties at larger diameters, but shall not exceed 0,12 % for austenitic steels.
Materialnumber
Chemical composition, % by mass
C Si Mn P S Cr Mo Ni Othermax. max. max. max.
Martensitic steels1.4006 0,08 to 0,15 1,0 1,5 0,04 0,030 11,0 to 13,5 max. 0,751.4034 0,43 to 0,50 1,0 1,0 0,04 0,030 12,5 to 14,51.4105 max. 0,08 1,0 1,5 0,04 0,035 16,0 to 18,0 0,20 to 0,601.4110 0,48 to 0,60 1,0 1,0 0,04 0,015 13,0 to 15,0 0,50 to 0,80 V max. 0,151.4116 0,45 to 0,55 1,0 1,0 0,04 0,030 14,0 to 15,0 0,50 to 0,80 V 0,10 to 0,201.4122 0,33 to 0,45 1,0 1,5 0,04 0,030 15,5 to 17,5 0,80 to 1,30 max. 1,0Austenitic steels1.4301 max. 0,07 1,0 2,0 0,045 0,030 17,0 to 19,5 8,0 to 10,5 N max. 0,111.4305 max. 0,10 1,0 2,0 0,045 0,15 to 0,35 17,0 to 19,0 8,0 to 10,0 Cu max. 1,00 / N max. 0,111.4310 0,05 to 0,15 2,0 2,0 0,045 0,015 16,0 to 19,0 max. 0,80 6,0 to 9,5 N max. 0,111.4401 max. 0,07 1,0 2,0 0,045 0,030 16,5 to 18,5 2,00 to 2,50 10,0 to 13,01.4435 max. 0,03 1,0 2,0 0,045 0,030 17,0 to 19,0 2,50 to 3,00 12,5 to 15,0 N max. 0,111.44391) max. 0,03 1,0 2,0 0,045 0,025 16,5 to 18,5 4,00 to 5,00 12,5 to 14,5 N 0,12 to 0,221.45291) max. 0,02 0,5 1,0 0,030 0,010 19,0 to 21,0 6,00 to 7,00 24,0 to 26,0 N 0,15 to 0,25 / Cu 0,5 to 1,51.45391) max. 0,02 0,7 2,0 0,030 0,010 19,0 to 21,0 4,00 to 5,00 24,0 to 26,0 N max. 0,15 / Cu 1,2 to 2,01.44621) max. 0,03 1,0 2,0 0,035 0,015 21,0 to 23,0 2,50 to 3,50 4,5 to 6,5 N 0,10 to 0,221.4568 max. 0,09 0,7 1,0 0,040 0,015 16,0 to 18,0 6,5 to 7,8 Al 0,70 to 1,501.4571 max. 0,08 1,0 2,0 0,045 0,030 16,5 to 18,5 2,00 to 2,50 10,5 to 13,5 Ti 5xC 0,70
1) Austenitic stainless steels with particular resistance to chloride induced stress corrosion. The risk of failure of bolts, screws and studs by chloride induced stress corrosion (for example in indoor swimming pools) can be reduced by using the materials marked in the table.
Austenitic stainless steels are divided into 5 main groups whose chemical compositions are as follows:
Chemical composition of austenitic stainless steels
according to ISO 3506
Chemical composition of corrosion resistant stainless steels
Materials screws & nuts
Stainless steel fasteners
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Material designation A1 A2 A3 A4 A5Material number 1.4300 1.4301 1.4541 1.4401 1.4436
1.4305 1.4303 1.4590 1.4435 1.45711.4306 1.4550 1.4439 1.4580
Properties for machining Standard quality Highest resistance to corrosion rust-resistant to a certain
degree rust-resistant rust-resistant
corrosion-resistant to a certain degree
acid-resistant highly acid-resistant
weldable to a certain degree weldable to a certain degree easily weldableA3, A5 as A2, A4 but stabilised against intergranular corrosion following welding, annealing or when used at high temperatures.
Further details on the chemical stability of rust-resistant and acid-resistant steels can be found on
Page T.023
Figure gives the approximate time for austenitic stainless steels, grade A2 (18/8 steels), with different carbon contents in the tempera-ture zone between 550 C and 925 C before risk of intergranular corrosion occours.
Note With lower carbon contents, the resistance against intergranu-lar corrosion is improved.
Distinctive properties of stainless steels
Time-temperature diagram of intergranular corrosion in austenitic stainless steels
Time in minutes
Tem
pera
ture
in C
Materials screws & nuts
Stainless steel fasteners
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Austenitic steels A1, A2 and A4 obtain their resistance to corrosion through a surface protective layer of oxide. If this is damaged it uses atmospheric oxygen to regenerate itself. If access to atmospheric oxygen is blocked by an unfavourable style of construction or through dirt, then even these steels will corrode!
General rules: A2 above water, inland climate A4 under water, coastal climate A1 this steel contains small particles of sul-
phur, which gives it a good machinability. Its resistance to corrosion is lower than that of A2.
Please avoid: cracks, separation joints, pockets of water, poor ventilation, layers of dirt
The resistance to corrosion can be reduced in the presence of a coating (prevents access to the air), or chemical blackening or a roughening of the surface.
Media containing chlorine can under certain conditions lead to dangerous inter-crystalline corrosion. This is often very difficult to see from the outside, and can lead to a sudden failure of the steel part.
ISO standard 3506 defines rust and acid-resistant steels. It also contains details of their mechanical properties, chemical compo-sition and a number of notes on the selection of the right steel for high and low temperature applications.
The reference data with respect to corrosion resistance Indications on resistance to corrosion are preferably obtained from laboratory and practical trials!Ask for information on our Bossard Analysis service.
Attention Martensitic chrome steels (e.g. 1.4110, 1.4116, 1.4112)
are normally used for corrosion-resistantretaining rings and washers. The corrosion resistance of these steels is lower than that of austenitic chrome-nickel steels.
Recent experience indicates that there is a risk of stress corrosion cracking. In order to reduce this risk the depth of the nuts can be selected so that the fitted rings are not subjected to stress. This will reduce their load-bearing capacity.
Advantages Avoidance of potential problems
Bright-finished surface, good appereance Rusty screws create a bad impression. The customer loses trust in the product.
Savety Corrosion reduces the strength and operational reliability of the fasteners.They become weak points.
No traces of red-rust Red rust can discolour white-coloured plastic components and textiles and make them unusable.
No risk to health Cutting yourself on a rusty part can lead to blood poisoning.
Food grade material Parts made from zinc-coated steel must not be allowed to come into contact with foodstuffs.
Lick-resistant Small children must not be able to get within reach of and lick small, zinc-coated or cadmium-coated parts.
Easy to clean and hygienic Products or efflorescences caused by corrosion can build up on bright-polished or zinc-coated fasteners which then become difficult to remove.
Austenitic chrome-nickel steel is almost entirely non-magnetic
Magnetic fasteners used in the construction of types of apparatus or measuring devices can lead to disruptions. Magnetic parts attract iron filings. This gives rise to additional problems of corrosion.
Good temperature resistance At temperatures above 80 C the chromating on zinc-plated and chrome-plated fasteners is destroyed.The corrosion resistance drops dramatically.
The screw and nuts are bright-polished and so always remain workable.
If the permissible thickness of the coating on galvanically finished screws is exceeded, the parts jam up when being assembled.
No problems during maintenance work Rusty screws or nuts just cannot be unscrewed. In order to disassemble the unit the fasteners have to bedestroyed, and this involves considerable force and effort.This often results in damage to the parts.
Ecologically-oriented use of austenitic screw elements into wood
The environmental influences lead to a chemical reaction at galvanized screws with the tannic acid existing inthe wood. A gray/black coloring which penetrate into the wood can not be eliminated any more.Due to the time restricted anti-corrosion protection and possible stress corrosion risk, the usage of highstrengthmartensitic steel is not recommended.In all corrosion relevant wood applications use of austenitic steels is recommended.
Chemical stability
based on information provided by the manufacturers
Technical arguments for the use of fasteners made from rust-resistant austenitic chrome-nickel steels A1, A2, A4
Materials screws & nuts
Stainless steel fasteners
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Screws
1) All values are calculated values and refer to the stressed cross-section of the thread.2) The elongation after fracture is to be determined for the whole screw and not for unscrewed test pieces.3) Strength of the screw is indicated by the head marking and defined by the applicable product standard.
Nuts
m = nut heightd = nominal thread diameter
The commercial quality of steel grades A2 and A4 is property class 70 (tensile strength 700 N/mm2). Strength of the screw is indicated by the head marking and defined by the applicable product standard.We keep a wide range available for you from stock.
Use of screws of property class 80 is only economically justifiable if the components are made from stainless steel (high strength).
Threads Minimum breaking torque MB min [Nm]Property class50 70 80
M1,6 0,15 0,2 0,24M2 0,3 0,4 0,48M2,5 0,6 0,9 0,96M3 1,1 1,6 1,8M4 2,7 3,8 4,3M5 5,5 7,8 8,8M6 9,3 13 15M8 23 32 37M10 46 65 74M12 80 110 130M16 210 290 330
Mechanical properties for fasteners made from austenitic stainless steel
according to ISO 3506
Reference values for 0,2 % Rp0, 2 at higher temperatures as % of the values at room temperature
according to ISO 3506
Steel grade1) 0,2 % Rp0,2
+100 C +200 C +300 C +400 C
A2, A4 85 % 80 % 75 % 70 %
For applicability at low temperature see Page T.017
1) applies for property classes 70 and 80
Steel group Steel grade
Property class Thread diameter range Tensile strengthRm min1) [N/mm2]
Stress at 0,2% perma-nent strain Rp 0,2 min1)[N/mm2]
Elongation after fractureAmin2)[mm]
Austenitic A1, A2 50 M39 500 210 0,6 dA3, A4 70 M393) 700 450 0,4 dA5 80 M393) 800 600 0,3 d
Steel group Steel grade
Property class Thread diameter range Stress under proof load SP min [N/mm2]
Nuts Style 1 thin nuts d Nuts Style 1 thin nutsm 0,8 d 0,5 d m < 0,8 d [mm] m 0,8 d 0,5 d m < 0,8 d
Austenitic A1, A2 50 025 M39 500 250A3, A4 70 035 M393) 700 350A5 80 040 M393) 800 400
Minimum breaking torque MB min for screws made from austenitic steel with threads M1,6 to M16 (normal thread)
according to ISO 3506
Materials screws & nuts
Stainless steel fasteners
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Marking of screws and nuts
according to ISO 3506
RequirementScrews and nuts made from stainless austenitic steels must be marked.
Caution Only those fasteners marked to standard will have the desired properties. Products not marked to standard will often only correspond to property classes A2-50 or A4-50.
ScrewsHexagon head screws, and hexagon or hexalobular socket head cap screws from nominal diameter M5 must be marked. The marking must show the steel group, the property class and the manufacturers mark. Locking screws must be marked on the shaft or screw end.
StudboltsBolts from nominal diameter M6 must be marked on the shank or the end of the thread with the steel group, the property class and the manufacturers mark.
Hexagon screws
A2-70
XYZA2
XYZ
A2-70
manufacturers mark
Property classSteel group
XYZ
XYZ
A2
A2-70
-70
When the marking is made with grooves and the property class is not indicated, property class 50 or 025 will apply.
It is possible that certain nuts would not fulfil the proof load requirements because of fine pitch thread or the geometry of the nut. These nuts may be marked with the steel grade, but shall not be marked with the property class.
> s
A4A2
Alternative groove marking(for steel grades A2 and A4 only)
Socket head cap screws
A A4-80 A
A4-80
NutsNuts from minimal diameter M5 must be marked with the steel group, the property class and the manufacturers mark.
Other markingsOther types of bolts and screws can be marked in the same way, where it is possible to do so and on the head portion only. Ad-ditional marking is allowed, provided it does not cause confusion.
Fasteners that do not fulfil the tensile or torsional requirements because of the geometry may be marked with the steel grade, but shall not be marked with the property class.
XYZ
A2
NoteMarkings analogous to ISO 898-1 using the supplementary 0(e.g. A2-070) are intended to be included in the next revision of ISO 3506-1.
Materials screws & nuts
Stainless steel fasteners
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Properties of screws and nuts made from copper alloys selection based on information provided by the manufacturers
Properties of screws and nuts made from aluminium alloys selection based on information provided by the manufacturers
The values in the table are for: density = 2,8 kg/dm3, coefficient of thermal expansion = 23,6 106 K1, modulus of elasticity = 70 000 N/mm2
Material designation EN AW-
MaterialnumberEN AW-
Old DINdesignation
Stage of preparation of the screws/nuts
Used for
Materialnumber
from EN28839
Rp 0,2[N/mm2]
Rm[N/mm2]
AS%
Al Mg5 5019 3.3555 AL 2 soft work hardened
< M14M14/M20
205200
310280
66
very good level of corrosion-resistance low strength
Al Si1 Mg Mn 6082 3.2315 AL 3 hardenedT6
< M6M6/M20
260250
320310
710
very good level of corrosion-resistance medium strength
Al Mg1 Si 0,8 Cu Mn 6013 hardenedT8
< M20 370 400 10 still a good level of corrosion-resistance high strength
Al Cu4 Mg Si 2017 A 3.1325 AL 4 hardenedT6 (F 42)
< M20 290 420 6 high strength mountings but lowest level of corrosion resistance1)
Al Zn6 Cu Mg Zr 7050 3.4144 hardenedT73 (F 50)
< M30 400 500 6 high strength mountings but lowest level of corrosion resistance
Al Zn5,5 Mg Cu 7075 3.4365 AL 6 hardenedT73 (F 51)
< M30 440 510 6
1) subject to stress corrosion cracking due to the high copper content
Materials screws & nuts
Fasteners of various materials
Material designation
Material number
Des.fromEN28839
State of structure
Density
Electricalconductivity
m
Coefficient ofthermal expansiona 30/100 C
Mechanical properties at 20 C
Used for
F = Rm/10 [kg/dm3] [ mm2] [mm/mmK] Rp 0,2[N/mm2]
Rm[N/mm2]
AS min.%
E-Modul[N/mm2]
E-Cu 58OF-Cu
2.0065
2.0040Cu 1
F20 soft
F201)8,94
58,0
56,017,0 10-6
< 150
< 320
200/270
> 350
40
7110 000
parts with a high electrical conductivity
CuZn 37(brass)
2.0321 10
2.0321 26Cu 2
F29 soft
F371)8,44 15,5 20,2 10-6
< 250
> 250
> 290
> 370
45
27110 000
normal fastenings
CuNi12 Zn24(nickel silver)
2.0730 10
2.0730 30
F34 soft
F54 soft8,67 4,4 18,0 10-6
< 290
> 440
330/440
540/640
40 8
125 000very good corrosion resistant, silver colors
CuNi1,5SiCuNi3Si
2.0853 732.0857 73
Cu 5
hardenedhardened
8,88,8
> 18,0> 15,0
16,0 10-616,0 10-6
> 540> 780
> 540> 830
1210
140 000144 000
high-strength fastening, with very good electrical conductivity
CuBe2 2.124 75 hardened 8,3 ~10 16,7 10-6 1 050/ 1 400
1 200/ 1 500
2 125 000 high-strength fastening, corrosion resistant, good electrical conductivity
Non-ferrous metal
1) cold strain hardening
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Fasteners of various materials
Threadsnominal
Minimum breaking torque1) [Nm] for material
CU1 CU2 CU3 CU4 CU5 AL1 AL2 AL3 AL4 AL5 AL6
M1,6 0,06 0,10 0,10 0,11 0,14 0,06 0,07 0,08 0,1 0,11 0,12M2 0,12 0,21 0,21 0,23 0,28 0,13 0,15 0,16 0,2 0,22 0,25M2,5 0,24 0,45 0,45 0,5 0,6 0,27 0,3 0,3 0,43 0,47 0,5M3 0,4 0,8 0,8 0,9 1,1 0,5 0,6 0,6 0,8 0,8 0,9M3,5 0,7 1,3 1,3 1,4 1,7 0,8 0,9 0,9 1,2 1,3 1,5M4 1 1,9 1,9 2 2,5 1,1 1,3 1,4 1,8 1,9 2,2M5 2,1 3,8 3,8 4,1 5,1 2,4 2,7 2,8 3,7 4 4,5
Minimum breaking torque for screws up to M5 according to ISO 8839
1) the torque test is to be carried out in according to ISO 898-7
DesignationMaterial number
Description and range of application, based on information provided by the manufacturer
Hastelloy B Highly corrosion resistant nickel-molybdenum alloy with excellent resistance against reducing media, in particular against all concentrations of hydrochloric acid up to boiling point, moist chlorine water gas, sulphuric acid, phosphoric acid and alkaline solutions. Adequate resistance to oxidising and reducing gases up to 800 C. Not recommended for strongly oxidising agents, iron and copper salts (see Hastelloy C).
Application: Components subject to strong chemical action, turbo-superchargers for jet engines etc.
B-2 2.4617B-3 2.4600
Hastelloy C Highly corrosion resistant nickel-chrome-molybdenum alloy with particularly high resistance against aggressive, oxidising andreducing media bleach solutions which contain free chlorine, chlorites, hypochlorites, sulphuric acid and phosphoric acid,organic acids such as vinegar and formic acid, solutions of nitrates, sulphates and sulphites, chlorides and chlorates, chromatesand cyanogen compounds.
Application: Components subject to strong chemical action, in chemical processes and plants, exhaust cleaning systems,in the production of fibres and paper, waste disposal etc.
C-4 2.4610C-22 2.4602C-276 2.4819C-2000 2.4675
Hastelloy G Nickel-chrome-iron alloy with excellent resistance to corrosion in oxidising media.Application: In chemical process engineering, particularly suitable for the production of phosphoric acid and nitric acid,desulphurization plant etc.
G-3 2.4619G-30 2.4603Inconel Nickel-chrome alloy with good industrial properties at high temperatures up to and above 1000C and an excellent resistance to
oxidation. Even resists corrosion from caustic materials.
Application: Heat treatment plant, nuclear energy technology, gas turbines, linings, ventilators and fans, chemical industry etc.
600 2.4816601 2.4851625 2.4856718 2.4668Monel Nickel-copper alloy with high strength and toughness over a wide range of temperatures.
Excellent resistance to corrosion by salt water and a large number of acids and alkaline solutions.Also suitable for parts used in presses and forges. Application: Valves, pumps, mountings, mechanically stressed components exposed to seawater etc.
400 2.4360K-500 2.4375
Nimonic The nickel-based chrome materials are alloys with a particularly high fatigue strength and resistance to oxidisation.For high mechanical stresses at temperatures up to 1000 C. A wide variety of penetration hardening methods allow therelaxation and creep behaviour to be controlled. Application: Rotating components subject to high temperatures, springs, fasteners, combustion chamber components, blades, washers, shafts etc.
75 2.495180A 2.495290 2.4969105 2.4634Titanium Reactive material with high strength in relation to its low density. Excellent resistance to corrosion in oxidising metals
which contain chloride.
Application: Components for weight-saving construction requiring high strength, subject to strong oxidising stresses, particularlyin the presence of chlorides. Chemical industry, seawater desalination, power station technology, medical technology etc.
Gr. 1 3.7025Gr. 2 3.7035Gr. 3 3.7055Gr. 4 3.7065Titanium Titanium alloy with a high specific strength.
Application: Components for the air and space industries, chemical processing technology, rotating components, fasteners,vehicle engineering etc.
Gr.5 3.7164/ 3.7165
Titanium Pure titanium alloyed with palladium. Increased resistance to corrosion, particularly against moist media which contain chloride.Grade 11 has increased properties of deformation.
Application: Chemical and petrochemical plant, housings etc.
Gr. 7 3.7235Gr. 11 3.7225
Special materials
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Thermoplastics
MaterialabbreviationDIN 7728
Density [g/cm3]DIN 53479
Tensile strength[N/mm2]DIN 53455
Fracture resistance %DIN 53455
Elasticity module[N/mm2]DIN 53457
Ball penetrationhardness, 10-sec Value [N/mm2]DIN 53456
Impact strength[kJ/m2]DIN 53453
Ductility[kJ/m2]DIN 53453
PE-HD 0,94/0,96 18/35 100/1 000 700/1 400 40/65 without fracture without fracturePE-LD 0,914/0,928 8/23 300/1 000 200/500 13/20 without fracture without fracturePP 0,90/0,907 21/37 20/800 1 100/1 300 36/70 without fracture 3/17POM 1,41/1,42 62/70 25/70 2 800/3200 150/170 100 8PA 6 1,13 70/85 200/300 1 400 75 without fracture without fracturePA 66 1,14 77/84 150/300 2 000 100 without fracture 15/20
Reference values of physical characteristics according to manufacturers data
MaterialabbreviationDIN 7728
Specificresistance[ cm]DIN 53482
Surface resistance []DIN 53482
Dielectric constant Dielectric loss factor Dielectric strength Surface leakage current DIN 53483 DIN 53483 resistance DIN 5348050 Hz 106 Hz 50 Hz 106 Hz [kV/25 m]
ASTM D 149[kV/cm]DIN 53481
KA KB/KC
PE-HD > 1017 1014 2,35 2,34 2,4 104 2,0 104 > 700 3 c > 600PE-LD > 1017 1014 2,29 2,28 1,5 104 0,8 104 > 700 3 b > 600PP > 1017 1013 2,27 2,25 < 4 104 < 5 104 800 500/650 3 c > 600POM > 1015 1013 3,7 3,7 0,005 0,005 700 380/500 3 b > 600PA 6 1012 1010 3,8 3,4 0,01 0,03 350 400 3 b > 600PA 66 1012 1010 8,0 4,0 0,14 0,08 400 600 3 b > 600
MaterialabbreviationDIN 7728
Operating temperature C Dimensional stability C Linear coefficientof expansion
Thermal conductivity
Specific heat
VSP (Vicat 5 kg)DIN 53460
ASTM D 6481,86/0,45
max. short therm max. permanent min. permanent [N/mm2] K1 10-6 [W/mK] [kJ/kg K]PE-HD 90/120 70/80 50 60/70 50 200 0,38/0,51 2,1/2,7PE-LD 80/90 60/75 50 35 250 0,32/0,40 2,1/2,5PP 140 100 0/30 85/100 45/120 150 0,17/0,22 2,0POM 110/140 90/110 60 160/173 110/170 90/110 0,25/0,30 1,46PA 6 140/180 80/100 30 180 80/190 80 0,29 1,7PA 66 170/200 80/120 30 200 105/200 80 0,23 1,7
Abbreviation SignificancePE-HD High density polyethylenePE-LD Low density polyethylenePP PolypropylenePOM Polymethylene, PolyacetalePA 6 Polyamide 6PA 66 Polyamide 6.6
Mechanical properties
Electrical properties
Thermal properties
Instructions for screws made of thermoplastic materials
Mechanical and physical properties, especially tensile strength and preload as well as colour, tolerances of threaded section and head geometry are subject to climatic conditions. Consult DIN 34810 and ISO 4759-1 for tolerance values, advice and assembly torques.
Preload can fall via stress relaxation. Instructions for construction and design are to be followed on the basis of VDI 2544.
Materials screws & nuts
Fasteners of various materials
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Chemical resistance
Materialabbreviation
Wat
er, c
old
Wat
er, h
ot
Aci
ds, d
ilute
Aci
ds, s
trong
Aci
ds, o
xidi
sed
Aci
d hy
drof
luor
ic
Det
egre
nts,
wea
k
Det
egre
nts,
stro
ng
Sal
ine
solu
tions
Hal
ogen
, dry
EC
alip
hatic
EC
chl
orin
ated
Alc
ohol
Eth
er-s
alic
ylic
Cet
one
Eth
er
Ald
ehyd
es
Am
ines
Org
anic
aci
ds
EC
aro
mat
ic
Fuel
s
Min
eral
oils
Gre
ases
, oils
EC
chl
orin
ated
,no
n-sa
tura
ted
Turp
entin
e
Waterabsorption, %ASTM D 570
PE-HD 1 1 1 1 0 3 1 1 1 0 1 3 1 1 1 3 3 1 1 3 3 1 1 0 0 < 0,01
PE-LD 1 1 3 0 3 1 1 1 0 1 0 3 3 3 0 1 0 0 3 3 0 0 < 0,01
PP 1 1 1 3 0 3 1 1 1 3 1 0 1 3 3 0 1 1 3 3 3 1 1 0 0 0,01 to 0,03
POM 1 1 3 0 0 0 1 1 1 0 1 1 1 0 3 1 3 3 1 3 1 1 1 1 3 0,22 to 0,25
PA 6 1 3 0 0 0 0 1 3 1 0 1 3 1 1 1 1 3 1 3 1 1 1 0 3 3 1,3 to 1,9
1 resistant 3 resistant with reservation 0 inconstant
Abbreviation SignificancePE-HD High density polyethylenePE-LD Low density polyethylenePP PolypropylenePOM Polymethylene, PolyacetalePA 6 Polyamide 6
Materials screws & nuts
Fasteners of various materials
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Elastomere
Material shortmarkISO 1629
CR FPM NBR EPDM TPE
Material designation Chloropren-Caoutchouc
Flourine-Caoutchouc
Acrylonitrile-Buta-diene-Caoutchouc
Ethylene-Propylene-Diene-Caoutchouc
ThermoplasticElastomer
Combustibility UL 94 - V2 UL 94 - V2 UL 94 HB UL 94 HB UL 94 HBTemperature range1)
min. 30 C 20 C 30 C 40 C 30 Cmax. continually +100 C +200 C +120 C +130 C +80 C
intermittent +120 C +280 C +150 C +170 C +120 C
Combustibility
Chemical resistance2)
Material shortmarkISO 1629
CR FPM NBR EPDM TPE
Material designation Chloropren-Caoutchouc
Flourine-Caoutchouc
Acrylonitrile-Butadiene-Caoutchouc
Ethylene-Propylene-Diene-Caoutchouc
ThermoplasticElastomer
Alcohol A A A A ABenzine C A A C BDiesel oil C A A C BMineral oil B A A B BAnimal and vegetariangreases
B A A B A
Weak alkaline solution A B B A AStrong alkaline solution B C C A BWeak acids B A B A AStrong acids C A C A AWater C A C A AOzone C A C A A
2) The following details should be regarded as guidelines only. Any more definite information can only be given with reference to the particular application in hand. For example, a precision part may fail simply on account of a slight change in volume, or aggressive media may in fact be usable as cleansing agent if only briefly in contact with the material in question.
A Very good, chemical resistance. Constant action of medium causes no damage to plastic within a period of 30 days. The plastic may remain resistant over a period of several years.
B Good to limited chemical resistance. Constant action of medium may cause slight damage within a period of 7 to 30 days, this damage some times being reversible (swelling, softening, reduction in mechanical strength, discolouration).
C Low chemical resistance. Unsuitable for subjection to constant action of medium. Damage may occur immediately (reduction in mechanical strength, deformation, discolouration, cracks, dissolution).
1) Minus values in temperature range apply only to parts in idle state without impact stress.
Material shortmarkISO 1629
CR FPM NBR EPDM TPE
Material designation Chloropren-Caoutchouc
Flourine-Caoutchouc
Acrylonitrile-Butadiene-Caoutchouc
Ethylene-Propylene-Diene-Caoutchouc
ThermoplasticElastomer
halogen free yes yes yesphosphate free yes yes yes yes yessilicone free yes yes yes yes yes
Chemical ingredients
Materials screws & nuts
Fasteners of various materials
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T.031 Twww.bossard.com Bos
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.01Corrosion protection
Galvanic process
Fasteners with electroplated coatingsaccording to ISO 4042
Galvanizing Passivation. Galvanizing followed by passivationof fasteners is a procedure which has proven itself in terms of both corrosion resistance and appearance. We can offer you an extensive assortment from our range in stock.
Passivation (chromalize) takes place immediately after the galvanizing, and is made by briefly dipping the part in solutions of chromic acid. The chromate treatment increases the corrosionprotection and prevents tarnishing and discoloration of the zinc coating. The protective effect of the layer of chromate differs with the different types of procedure (see the table!).
New developments in processes involving chromium (VI)-free coatings offering the same or similar protective effect spurred onwards by environmental regulations due to EU Direc-tives 2000/53/EC (ELV) und 2002/95/EC (RoHS). Until now normal practice has been to use galvanic zinc coatings (ISO 4042) with chromate treatment based on chromium (VI) for the corrosion protection of fasteners. The new surface treatments based on chromium (VI) free systems usually require a more complex process control and where necessary additional cover layers, since the self-healing effect is missing. Long-term ex-perience gained under working conditions is largely not available and such experience is also influenced by specific conditions such as handling, transport and feeder devices. Consequently it is recommended that a review be made through the adjustment for the different operating conditions met in practice.
Types of procedure used for the passivation of electroplated zinc coatingsProtective effect of zinc coatings with passivation under conditions of salt spray testing to ISO 9227 (DIN 50021 SS).
Types of process Designation of the passivation
Chromate coating own color
Nominal thickness on the coating
First appearance of
White rust, hours Red rust, hoursm h h
Colorless passivation A transparent 3 2 125 6 248 6 48
Blue passivation B transparent, 3 6 12with a tinge of blue 5 12 36(standard) 8 24 72
Yellow chromated C yellowish lustre toyellow-brown iridescent
3 24 245 48 728 72 120
Olive chromated D olive-green toolive-brown (rare)
3 24 245 72 968 96 144
Black chromated1) BK blackish brown toblack (decorative)
3 5 12 8 24 72
1) On edges, the edges of the Phillips recess etc. use of the drum process means that you can practically always expect the black chromate coating to be rubbed off here and the underlying light-colored zinc coating to become locally visible.
Reduction of the risk of hydrogen embrittlement (ISO 4042)There is a risk of failure due to hydrogen embrittlement in galvani-cally finished fasteners which are under tensile stress and which are made from steels with tensile strengths of Rm 1000 N/mm2, corresponding to 320 HV.
Heat treatment (tempering) of the parts, e.g. after the acid pick-ling or metal coating process, will reduce the risk of breakage.However it cannot be guaranteed that the risk of hydrogen embrittlement will be removed completely. If the risk of hydrogen embrittlement must be reduced, then other coating proceduresshould be considered.
Alternative methods of corrosion protection or coating should therefore be selected for parts which are important to safety, alternatives such as anorganic zinc coating, mechanical galvanization or a switch to rust- and acid-resistant steels.
Where the method of fabrication allows, fasteners in classes 10.9 ( HV320) are provided with an anorganic zinc coating or are mechanically galvanized.The user of the fasteners knows the purposes and requirements for which the fasteners are to be used and he must specify the appropriate type of surface treatment!
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T.032T www.bossard.com Bos
sard,
EN,
2014
.01
Bo
ssard
, EN,
2014
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Corrosion protection
ThreadpitchP
Nominalthreaddiameter1)d1
Internal thread External threadTolerance position G Tolerance position g Tolerance position f Tolerance position e
Funda-mentalde-viation
Coatingthickness
Funda-mentalde-viation
Nom. coating thickness Funda-mentalde-viation
Nom. coating thickness Funda-mentalde-viation
Nom. coating thickness
max.2) max.3) max.2) max.3) max.2) max.3)
Overalllength
Nom. length l Overalllength
Nom. length l Overalllength
Nom. length l
5d 10d 15d 5d 10d 15d 5d 10d 15d
[mm] [mm] [m] max. [m] [m] [m] [m] [m] [m] [m] [m] [m] [m] [m] [m] [m] [m] [m] [m]0,2 +17 3 17 3 3 3 3 0,25 1; 1,2 +18 3 18 3 3 3 3 0,3 1,4 +18 3 18 3 3 3 3 0,35 1,6 (1,8) +19 3 19 3 3 3 3 34 8 8 5 5 0,4 2 +19 3 19 3 3 3 3 34 8 8 5 5 0,45 2,5 (2,2) +20 5 20 5 5 3 3 35 8 8 5 5 0,5 3 +20 5 20 5 5 3 3 36 8 8 5 5 50 12 12 10 80,6 3,5 +21 5 21 5 5 3 3 36 8 8 5 5 53 12 12 10 80,7 4 +22 5 22 5 5 3 3 38 8 8 5 5 56 12 12 10 80,75 4,5 +22 5 22 5 5 3 3 38 8 8 5 5 56 12 12 10 80,8 5 +24 5 24 5 5 3 3 38 8 8 5 5 60 15 15 12 101 6 (7) +26 5 26 5 5 3 3 40 10 10 8 5 60 15 15 12 101,25 8 +28 5 28 5 5 5 3 42 10 10 8 5 63 15 15 12 101,5 10 +32 8 32 8 8 5 5 45 10 10 8 5 67 15 15 12 101,75 12 +34 8 34 8 8 5 5 48 12 12 8 8 71 15 15 12 102 16 (14) +38 8 38 8 8 5 5 52 12 12 10 8 71 15 15 12 102,5 20 (18; 22) +42 10 42 10 10 8 5 58 12 12 10 8 80 20 20 15 123 24 (27) +48 12 48 12 12 8 8 63 15 15 12 10 85 20 20 15 123,5 30 (33) +53 12 53 12 12 10 8 70 15 15 12 10 90 20 20 15 154 36 (39) +60 15 60 15 15 12 10 75 15 15 15 12 95 20 20 15 154,5 42 (45) +63 15 63 15 15 12 10 80 20 20 15 12 100 25 25 20 155 48 (52) +71 15 71 15 15 12 10 85 20 20 15 12 106 25 25 20 155,5 56 (60) +75 15 75 15 15 15 12 90 20 20 15 15 112 25 25 20 156 64 +80 20 80 20 20 15 12 95 20 20 15 15 118 25 25 20 15
Coating thicknesses for parts with external thread
according to ISO 4042
1) Information for coarse pitch threads is given for information. The determining characteristic is the thread pitch.2) Maximum values of nominal coating thickness if local thickness measurement is agreed.3) Maximum values of nominal coating thickness if batch average thickness measurement is agreed.
If no particular plating thickness is specified, the minimum plating thickness is applied. This is also considered the standard plating thickness.
In the case of parts with very long thread or small dimensions ( M4), an irregular coating thickness may occur due to the processing. This can cause assembly problems. Possible solution: Use of a chemical nickel plating or stainless steel screws A2 or A4.
External threads are normally fabricated in tolerance zone 6g.
e and f tolerance are not common and require special methods of screw manufacture. Minimum quantities, longer delivery periods and higher prices may make these economically unvi-able. An alternative is to use parts made from stainless steel A2. Internal threads have a thinner coating due to technical reasons. How ever, this has no significance in practical use because when assembled these are protected by the coating of the external thread of the screw.
Measuring points for coating thickness
Measuring point
Measuring point
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T.033 Twww.bossard.com Bos
sard,
EN,
2014
.01
Bo
ssard
, EN,
2014
.01
Further galvanic coating processes
Process Details
Nickel-plating Nickel-plating is decorative and provides effective corrosion protection. A hard coating, used in the electrical appliance and telecommunications industries. No coating abrasion occurs, especially with screws. Improves protection against impregnation, see table below.
Veralisation A special method of hard nickel-plating.
Chromium-plating Usually following nickel-plating. Coating thickness about 0,4 m.Chromium is decorative, enhances resistance to tarnishing and improves corrosion protection.Bright chromium-plated: high brightness finish.Matt chromium-plated: matt lustre (silk finish).Polished chromium-plated: grinding, brushing and polishing of the surface prior to coating electrolytically (done by hand).Drum chromium plating not possible.
Brass-plating Brass plating is mainly applied for decorative purposes. In addition, steel components are brass-plated in order toimprove the adhesion of rubber to steel.
Copper-plating Used when necessary as intermediate coating prior to nickel-plating-chromium-plating and silver-plating. Used for decorati