Chemical composition as per ISO 898-1 for typical grades
| Class | Material and Treatment | C min. | C max. | P max. | S max. | B max. | Tempering temp. [°C] |
|---|---|---|---|---|---|---|---|
| 8.8 | carbon steel with additives (e.g. b, mn or cr) quenched and tempered | 0.15 (d) | 0.40 | 0.025 | 0.025 | 0.003 | 425 |
| 8.8 | carbon steel quenched and tempered | 0.25 | 0.55 | 0.035 | 0.025 | 0.003 | 425 |
| 10.9 | carbon steel with additives (e.g. b, mn or cr) quenched and tempered | 0.15 (d) | 0.35 | 0.025 | 0.025 | 0.003 | 340 |
| 10.9 | carbon steel quenched and tempered | 0.25 | 0.55 | 0.025 | 0.025 | 0.003 | 425 |
| 10.9 | carbon steel with additives (e.g. b, mn or cr) quenched and tempered | 0.20 (d) | 0.55 | 0.025 | 0.025 | 0.003 | 425 |
| 10.9 | alloy steel quenched and tempered (g) | 0.20 | 0.55 | 0.025 | 0.025 | 0.003 | 425 |
| 12.9 | alloy steel quenched and tempered (g) | 0.28 | 0.50 | 0.025 | 0.025 | 0.003 | 380 |
(d) in case of plain carbon boron steel with a carbon content below 0.25% (ladle analysis), min manganese 0.6% for 8.8 and 0.7% for 10.9
(g) alloy steel shall contain one of the following elements: chromium 0.30%, nickel 0.30%, molybdenum 0.20%, vanadium 0.10%
Mechanical and physical properties as per ISO 898-1 for typical grades
| Mechanical or Physical Property | Class 8.8 (M16 and below) | Class 8.8 (above M16) | Class 10.9 | Class 12.9 | |
|---|---|---|---|---|---|
| Tensile strength (MPa) | nom. | 800 | 800 | 1000 | 1200 |
| Tensile strength (MPa) | min. | 800 | 830 | 1040 | 1220 |
| Stress at 0.2% non-proportional elongation (yield) (MPa) | nom. | 640 | 640 | 900 | 1080 |
| Stress at 0.2% non-proportional elongation (yield) (MPa) | min. | 640 | 660 | 940 | 1100 |
| Stress under proof load (MPa) | nom. | 580 | 600 | 830 | 970 |
| Elongation after fracture for machined test piece (%) | min. | 12 | 12 | 10 | 8 |
| Reduction of area after fracture for machined test piece (%) | min. | 52 | 52 | 48 | 44 |
| Impact strength, charpy v-notch (J) | min. | 27 | 27 | 27 | (under investigation) |
Hardness requirement as per ISO 898-1 for typical grades
| Hardness Scale | Class 8.8 (M16 and below) | Class 8.8 (above M16) | Class 10.9 | Class 12.9 |
|---|---|---|---|---|
| Vickers, HV | 250-320 | 255-335 | 320-380 | 385-435 |
| Brinell, HB | 238-304 | 242-318 | 304-361 | 366-414 |
| Rockwell, HRC | 22-32 | 23-34 | 32-39 | 39-44 |
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