Metric Steel Bolts - Grades and Property Classes
Metric steel bolts, screws and studs - proof and tensile strength.
For metric bolts strength is according ISO 898 Mechanical properties of fasteners made of carbon steel and alloy steel described by "property classes" with designations 4.6, 4.8, 5.8, 8.8, 9.8, 10.9 and 12.9.
| Property Class | Head Marking | Size Range (mm) | Minimum Proof Strength (106 Pa) | Minimum Tensile Strength (106 Pa) | Material |
|---|---|---|---|---|---|
| 4.6 |  |
M5 - M36 | 225 | 400 | Low or medium carbon steel |
| 4.8 |  |
M1.6 - M16 | 310 | 420 | Low or medium carbon steel |
| 5.8 |  |
M5 - M24 | 380 | 520 | Low or medium carbon steel |
| 8.8 |  |
M1.6 - M36 | 600 | 830 | Medium carbon steel, Q & T |
| 9.8 |  |
M1.6 - M16 | 650 | 900 | Medium carbon steel, Q & T |
| 10.9 |  |
M5 - M36 | 830 | 1040 | Low carbon martensite steel, Q & T |
| 12.9 |  |
M1.6 - M36 | 970 | 1220 | Alloy steel, Q & T |
- 1 Pa = 1 N/m2 = 1.4504×10-4 lb/in2 (psi)
