Grade 8.8 Carbon Steel Bolts
- Grade 8.8 is a widely used property class for carbon steel hex bolts. The figure combines a tensile strength indicator (800 MPa) with a class multiplier (0.8) giving a yield strength of approximately 640 MPa.
- These bolts are usually supplied with a protective coating such as zinc or hot-dip galvanising to counter corrosion of the carbon substrate.
Key properties
Typical reference values — confirm with a certificate.
| Property class | 8.8 |
|---|---|
| Tensile strength (reference) | ~800 MPa |
| Yield strength (reference) | ~640 MPa |
| Material | Low-carbon or medium-carbon steel (C35–C45) |
| Typical finish | Zinc plated, hot-dip galvanized, or black oxide |
Grades / designations
8.810.912.9 (higher classes on request)
Important notes
- Higher classes (10.9, 12.9) increase strength but reduce ductility and increase susceptibility to hydrogen embrittlement unless controlled.
- Coating thickness and surface treatment should match the environment and any lubrication factor required for torque.
- Always confirm the property class called for on the drawing rather than assuming 8.8.
Related content
Discuss your requirements
A drawing, sample reference or parts list is enough to start the conversation. Dimensions and commercial terms are confirmed with your quotation.