The products are mainly used to produce fasteners of class 8.8 ~ 10.9. Use of Products:10B21,10B28 and 10B33 are mainly used to produce fasteners of class 8.8 ~10.9, It has of uniform-chemicalcomposition, low percentage of harmful elements, high puruty,slight decarburisation, good surface quality,good cold heading perfomence, low rigidity. They also has characteristics of high intensity and good hardenability after heat treatment.
| 钢号 Grade | 化学成份（Chemical composition）％ | ||||||
| SAE Standard | C | Mn | Si | S | P | B | Al |
| 10B18 | 0.16~0.23 | 0.60~0.90 | 0.10Max | Max0.30 | Max0.30 | 0.0008~0.003 | Min0.020 |
| 10B21 | 0.18~0.23 | 0.60~0.90 | 0.10Max | Max0.30 | Max0.30 | 0.0008~0.003 | Min0.020 |
| 10B28 | 0.26~0.32 | 0.70~1.00 | 0.40Max | Max0.30 | Max0.30 | 0.0008~0.003 | Min0.020 |
| 10B30 | 0.28-0.34 | 0.70~1.00 | 0.10Max | Max0.30 | Max0.30 | 0.0008~0.003 | Min0.020 |
| 10B33 | 0.29~0.38 | 0.70~1.00 | 0.15~0.35 | Max0.35 | Max0.30 | 0.0008~0.003 | Min0.020 |
| 10B38 | 0.35~0.42 | 0.70~1.00 | 0.15~0.35 | Max0.35 | Max0.30 | 0.0008~0.003 | Min0.020 |
