China · GB
85
GB/T 699:2015 — Quality carbon structure steels
Chemical composition
| Element | min | max | Similar | Remarks |
|---|---|---|---|---|
| C | 0.82 | 0.9 | ||
| Cr | 0.25 | |||
| Cu | 0.25 | 热压力加工用钢铜含量应不大于0.20% | 热压力加工用钢铜含量应不大于0.20% | |
| Mn | 0.5 | 0.8 | ||
| Ni | 0.3 | |||
| P | 0.035 | |||
| S | 0.035 | |||
| Si | 0.17 | 0.37 |
Mechanical properties
| Heat treatment / condition | Yield strength | Tensile strength | Elongation | Reduction of area | Impact energy | Hardness |
|---|---|---|---|---|---|---|
| steel bars, quenched and tempered | ≥980 | ≥1130 | ≥6 | ≥30 | ||
| steel bars, hot rolled or | HB ≤302 | |||||
| steel bars, annealed | HB ≤255 |
Heat treatment
| Type | 3 | 4 |
|---|---|---|
| Heat-treatment process | Tempered | 480℃±50℃ |
| Heat-treatment process | Quenched | 820℃±20℃，保温不少于30min，油冷 |