10. 9级高强度螺栓ML20MnTiB热轧盘条的开发

通过控制钢中Ti、B的有效成分以保证钢的淬透性，以及采用合理的控轧控冷工艺以确保钢的高塑性和表面低硬度性能，山西新泰钢铁公司成功开发了高强度冷镦用钢ML20MnTiB的Φ20mm热轧盘条，其直接冷镦的冷镦合格率达到了98%以上，制成高强度六角螺栓后也完全满足10. 9级高强度螺栓的技术要求。

Development of ML20MnTiB Hot Rolled Coil Wire for 10.9 Grade Bolt

Through the effective composition control of Ti, B to ensure that the hardenability of the steel, and appropriate controlled rolling and accelerated cooling process to ensure high plasticity and low surface hardness of steel, the high strength cold heading with a diameter of Ф20mm hot rolled coil wire ML20MnTiB was developed at Shanxi Xintai Steel Corp. Its direct cold heading passing rate was reached more than 98 %, and the high strength six corner bolt which was manufactured by ML20MnTiB coil wire could be fully meet the require- ments of high strength bolt 10.9 level technology.