carbon-steelISO 898-1
Property Class 5.8
One step above 4.8. Widely used where moderate preload is enough.
Tensile Rm520 MPa
Yield Rp0.2420 MPa
HardnessHRB 82–95
Nut class5
Mechanical properties
- Property class
- Property Class 5.8
- Defined in
- ISO 898-1
- Tensile strength Rm (min)
- 520 MPa
- Yield strength Rp0.2 (min)
- 420 MPa
- Hardness
- HRB 82–95
- Matching nut class
- 5
- Material
- Carbon Steel
Where this grade is used
The property class is stamped on the head of bolts and screws of M5 and larger, so a 5.8 bolt is marked 5.8. A Property Class 5.8 fastener is specified where the joint needs a 0.2 % proof strength of about 420 MPa or less. Always pair it with a nut of ISO 898-2 class 5 or higher, so the bolt fails before the thread strips.