Mechanical and physical property for the class4.8 class8.8 class10.9 class12.9 bolts, screws and studs
Mechanical property of bolts, screws, and studs are essential characteristics that determine their performance in various applications. These properties include:
1. Tensile Strength: The maximum axial load (tensile force) a fastener can withstand without breaking. It’s a crucial property for bolts and studs as they often experience tension in their applications.
2. Yield Strength: The amount of stress a fastener can withstand without undergoing permanent deformation. Once a fastener surpasses its yield strength, it won’t return to its original shape after the load is removed.
3. Elongation: Elongation measures how much a fastener can stretch before breaking. It’s expressed as a percentage of the original length.
4. Hardness: Fasteners need to be sufficiently hard to resist wear and deformation. Common hardness measurements include Rockwell hardness and Brinell hardness.
| Mechanical or physical property | Property class | ||||||||
| 4.6 | 4.8 | 5.6 | 6.8 | 8.8 (d≤16mm) | 8.8(d＞16mm) | 10.9 | 12.9 | ||
| Tensile strength, Rm, MPa | nom. | 400 | 400 | 500 | 600 | 800 | 800 | 1000 | 1200 |
| min. | 400 | 420 | 500 | 600 | 800 | 830 | 1040 | 1220 | |
| Lower yield strength, ReL d, MPa | nom. | 240 | - | 300 | - | - | - | - | - |
| min. | 240 | - | 300 | - | - | - | - | - | |
| Stress at 0,2 % nonproportional elongation, R p0,2, MPa | nom. | - | - | - | - | 640 | 640 | 900 | 1080 |
| min. | - | - | - | - | 640 | 660 | 940 | 1100 | |
| Percentage elongation after fracture for machined test pieces, A, % | min. | 22 | - | 20 | - | 12 | 12 | 10 | 8 |
| Percentage reduction of area after fracture for machined test pieces, Z, % | min. | - | 52 | 48 | 44 | ||||
| Vickers hardness, HV F W 98 N | min. | 120 | 130 | 155 | 190 | 250 | 255 | 320 | 385 |
| max. | 220 | 320 | 335 | 380 | 435 | ||||
| Rockwell hardness, HRC | min. | - | - | - | - | 22 | 23 | 32 | 39 |
| max. | - | - | - | - | 32 | 34 | 39 | 44 | |
Select fasteners with appropriate mechanical properties for the specific application to ensure safety and reliability. These properties may vary depending on factors like material, size, and manufacturing processes.