Property class

Material and heat treatment

Chemical composition limit (cast analysis, %)^a

Tempering temperature ⁰C

Min.

C

P

S

B^b

min.

max.

max.

max.

max.

8.8

Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered

0,15^e

0,40

0,025

0,025

0,003

425

Carbon steel quenched and tempered

0,25

0,55

0,025

0,025

Alloy steel quenched and tempered^g

0,20

0,55

0,025

0,025

Mechanical or physical property

Tensile strength, R_m, MPa

Stress at 0,2 % non-proportional elongation, R_p0,2, MPa

Stress under proof load, S_p^f, MPa

Proof strength ratioS_p,nom/R_eL,min

Percentage elongation after fracture for machined test pieces, A, %

Percentage reduction of area after fracture for machined test pieces, Z, %

Height of non-decarburized thread zone, E, mm

Depth of complete decarburization in the thread, G, mm

Reduction of hardness after retempering, HV

Impact strength, K_V^ij, J

nom.^c

min.

nom.c

min.

nom.

min.

min.

min.

max.

max.

min.

8.8

d≤ 16 mm^a

800

800

640

640

580

0,91

12

52

1/2 H₁

0,015

20

27

d> 16 mm^b

830

640

660

600

0,91

0,016

21

27

Mechanical or physical property

Vickers hardness,

HV F ≥98 N

Brinell hardness, HBW F = 30 D²

Rockwell hardness, HRC

Surface hardness, HV 0,3

min.

max.

min.

max.

min.

max.

max.

8.8

D ≤ 16 mm^a

250

320

245

316

22

32

-

D > 16 mm^b

255

335

250

331

23

34

-