alloy-steelISO 898-1
Property Class 10.9
High strength alloy steel. Used in automotive suspension and structural joints.
Tensile Rm1040 MPa
Yield Rp0.2940 MPa
HardnessHRC 32–39
Nut class10
Mechanical properties
- Property class
- Property Class 10.9
- Defined in
- ISO 898-1
- Tensile strength Rm (min)
- 1040 MPa
- Yield strength Rp0.2 (min)
- 940 MPa
- Hardness
- HRC 32–39
- Matching nut class
- 10
- Material
- Alloy Steel
Where this grade is used
The property class is stamped on the head of bolts and screws of M5 and larger, so a 10.9 bolt is marked 10.9. A Property Class 10.9 fastener is specified where the joint needs a 0.2 % proof strength of about 940 MPa or less. Always pair it with a nut of ISO 898-2 class 10 or higher, so the bolt fails before the thread strips.