item | national standard steel shot | high quality steel shot | |
Chemical composition% | C | 0.85-1.20 | 0.10-0.20 |
Si | 0.40-1.20 | 0.10-0.35 | |
Mn | 0.60-1.20 | 0.35-1.50 | |
S | <0.05 | <0.05 | |
P | <0.05 | <0.05 | |
hardness | steel shot | HRC40-50 HRC55-62 | HRC42-48 HRC48-54 |
density | steel shot | ≥7.20 g/cm3 | 7.4g/cm3 |
metallographic structure | Tempered martensite or troostite | tempered martensite + bainite | |
appearance | round hollow grain﹤10% crack<15% | round hollow grain﹤5% crack <10% |