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High-Strength Hex Bolts — Classes 8.8 / 10.9 / 12.9
- Standards
- GB/T 5783 / DIN 933 / DIN 931
- Property classes
- 8.8 / 10.9 / 12.9
- Materials
- Medium-carbon steel / 40Cr / 35CrMo / SCM435 alloy steel
- Finishes
- Black oxide / zinc plating / hot-dip galvanizing / Dacromet
- Size range
- M4–M20; custom sizes available
- Mechanical performance
- ISO 898-1 requirements, as stated in the original catalog
Class 8.8 — Quenched and Tempered Medium-Carbon Steel
| Property class 8.8 (quenched and tempered medium-carbon steel) | ||||
|---|---|---|---|---|
| Size | Tensile strength, min. | Yield strength, min. | Hardness range (HRC) | Suggested tightening torque (N·m) |
| M4 | 800 MPa | 640 MPa | 22 - 32 | 3.0 |
| M6 | 800 MPa | 640 MPa | 22 - 32 | 10.5 |
| M8 | 800 MPa | 640 MPa | 22 - 32 | 26 |
| M10 | 800 MPa | 640 MPa | 22 - 32 | 49 |
| M12 | 800 MPa | 640 MPa | 22 - 32 | 85 |
| M16 | 800 MPa | 640 MPa | 22 - 32 | 210 |
| M20 | 800 MPa | 640 MPa | 22 - 32 | 410 |
Class 10.9 — Quenched and Tempered Low-Alloy Steel
| Property class 10.9 (quenched and tempered low-alloy steel) | ||||
|---|---|---|---|---|
| Size | Tensile strength, min. | Yield strength, min. | Hardness range (HRC) | Suggested tightening torque (N·m) |
| M4 | 1040 MPa | 940 MPa | 32 - 39 | 4.5 |
| M6 | 1040 MPa | 940 MPa | 32 - 39 | 15 |
| M8 | 1040 MPa | 940 MPa | 32 - 39 | 37 |
| M10 | 1040 MPa | 940 MPa | 32 - 39 | 70 |
| M12 | 1040 MPa | 940 MPa | 32 - 39 | 120 |
| M16 | 1040 MPa | 940 MPa | 32 - 39 | 295 |
| M20 | 1040 MPa | 940 MPa | 32 - 39 | 580 |
Class 12.9 — Quenched and Tempered Alloy Steel
| Property class 12.9 (quenched and tempered alloy steel) | ||||
|---|---|---|---|---|
| Size | Tensile strength, min. | Yield strength, min. | Hardness range (HRC) | Suggested tightening torque (N·m) |
| M4 | 1220 MPa | 1100 MPa | 39 - 44 | 5.2 |
| M6 | 1220 MPa | 1100 MPa | 39 - 44 | 18 |
| M8 | 1220 MPa | 1100 MPa | 39 - 44 | 43 |
| M10 | 1220 MPa | 1100 MPa | 39 - 44 | 85 |
| M12 | 1220 MPa | 1100 MPa | 39 - 44 | 145 |
| M16 | 1220 MPa | 1100 MPa | 39 - 44 | 360 |
| M20 | 1220 MPa | 1100 MPa | 39 - 44 | 700 |
Values reproduced from the original website. Torque values are reference values, not assembly instructions; confirm joint design, lubrication and application conditions before use.
Applications
- 8.8: General machinery, automotive components and construction supports.
- 10.9: Heavy trucks, wind energy, tower cranes and structural steel connections.
- 12.9: Toolmaking and heavily loaded machinery components subject to alternating impact.
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