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
Property classes are stamped on the head of bolts and screws above 5 mm diameter. A Property Class 5.8 fastener is specified where the joint needs a proof load of roughly 378 MPa or less. Always match the bolt class with a nut of class 5 or higher so the bolt fails before the thread strips.