ISO 898-1 Grade 12.9

ISO 898-1 Grades

Mechanical properties of fasteners made of carbon steel and alloy steel Grade 12.9

The Grade 12.9 Bolts, screws, and studs with specified property classes - coarse thread and fine pitch thread

The ISO 898-1:2013 Grade 12.9 specification covers carbon steel bolts and studs ranging from M-6 to M-64 diameter. We use high carbon steel material and high alloy steel raw materials to achieve the required properties of grade 12.9 . There are three popular grades in this standard, 8.8, 10.9 and 12.9 which denote material hardness strength and their respective mechanical properties.

ISO 898-1:2013 Grade 12.9
12.9 Socket head cap screws, Allen bolts
ISO 898-1:2013 grade 12.9 Chemical properties

Property class

Material and heat treatment

Chemical composition limit (cast analysis, %)a

Tempering temperature ⁰C

Min.

C

P

S

Bb

min.

max.

max.

max.

max.

12.9f h i

Alloy steel quenched and temperedg

0,30

0,50

0,025

0,025

0,003

425

12.9f h i

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

0,28

0,50

0,025

0,025

0,003

380

ISO 898-1:2013 grade 12.9 Mechanical properties

Mechanical or physical property

Tensile strength, Rm, MPa

Stress at 0,2 % non-proportional elongation, Rp0,2, MPa

Stress under proof load, Spf, MPa

Proof strength ratio

Sp,nom/ReL,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</p>

Impact strength, KVij, J

nom.c

min.

nom.c

min.

nom.

min

min.

min.

min.

max.

max.

min.

12.9

1 200

1220

1080

1100

970

0,88

8

44

3/4 H1

0,018

23

k

ISO 898-1:2013 grade 12.9 Recommended hardness

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.

12.9

385

435

380

429

39

44

435