Mechanical properties of screws and studs according to EN ISO 898-1:2013 Property class 4.6 to 12.9.

No. Mechanical properties property classes
4,6 4,8 5,6 5,8 6,8 8.8
d<16 mmᵃ
8,8
d>16 mmᵇ
9,8
d<16 mm
10,9 12,9
1 Tensile strength, Rm, MPa nom. ° 400 500 600 800 900 1000 1200
min. 400 420 500 520 600 800 830 900 1040 1220
2 Lower proof stress ReL ᵈ, MPa nom. ᶜ 240 - 300 - - - - - - -
min. 240 - 300 - - - - - - -
3 Yield strength, Rp0.2, MPa nom. ᶜ - - - - - 640 640 720 900 1080
min. - - - - - 640 660 720 940 1100
4 Yield strength at 0.0048 d for whole screw, Rpf, MPa nom. ᶜ - 320 - 400 480 - - - - -
min. - 340ᵉ - 420ᵉ 480ᵉ - - - - -
5 Proof stress, Spᶠ, MPa nom. 225 310 280 380 440 580 600 650 830 970
Stress during proofing load testing  0,94 0,91 0,93 0,90 0,92 0,91 0,91 0,90 0,88 0,88
6 Elongation after fracture (test specimen), A, % min. 22 - 20 - - 12 12 10 9 8
7 Contraction after fracture (test specimen), Z, % min. - 52 48 48 44
8 Elongation after fracture, Af (whole screw) min. - 0,24 - 0,22 0,20 - - - - -
9 Ductility in event of head soundness test Inget brott
10 Vickers hardness, HV
F ≥ 98 N
min. 120 130 155 160 190 250 255 290 320 385
max. 220ᵍ 250 320 335 360 380 435
11 Brinell hardness, HBW
F = 30 D²
min. 114 124 147 152 181 238 242 276 304 366
max. 209ᵍ 238 304 318 342 361 414
12 Rockwell hardness, HRB min. 67 71 79 82 89 -
max. 95,0ᵍ 99,5 -
Rockwell hardness, HRC min. - 22 23 28 32 39
max. - 32 34 37 39 44
13 Surface hardness, HV 0.3 max. - h h, i h, j
14 Min. height of non-decarburised zone,
E, mm
min. - ½ H1 ⅔ H1 ¾ H1
Max. depth of complete decarburisation,
G, mm
max. - 0,015
15 Reduction in hardness after re-annealing, HV max. - 20
16 Fracture torque, MB,Nm min. - regarding to ISO 898-7
17 Impact strength, Kᵥᵏ˴ˡ, J min. - 27 - 27 27 27 27 m
18 Surface defects ISO 6157-1ⁿ ISO
6157-3

a)  The values do not apply to structural bolts.
b) For structural bolts ≥ M12.
c) Nominal values are only specified in order to indicate property class in the designation system.
d) If the lower proof stress ReL cannot be determined, it is permitted to measure the yield strength Rp0.2.
e) For property classes 4.8, 5.8 and 6.8, the values for Rpf min are under investigation.
f) Proof loads are specified in SS-EN ISO 898-1:2013.
g) Hardness determined at the end of the screw must be max. 250 HV, 238 HB or 99.5 HRB.
h) The surface hardness may not be more than 30 Vickers units higher than the measured core hardness determined with HV 0.3.
i) No surface hardness exceeding 390 HV is permitted.
j) No surface hardness exceeding 435 HV is permitted.
k) The values are determined at -20˚C.
l) Applies to d ≥ 16 mm.
m) Value Kᵥ is under investigation.
n) ISO 6157-3 can be used by agreement between manufacturer and purchaser.
o) Sp,nom / ReL min or Sp,nom / Rp0.2 min or Sp,nom / Rpf min