大直径锻造耐磨钢球热处理工艺的优化

Study on the optimization of heat treatment technology of large diameter forging wear-resistant steel ball

通过对淬火温度、自回火温度和贝氏体等温转变时间对大直径锻造钢球的硬度、冲击韧性以及组织的影响的研究,对比分析了不同热处理工艺的微观组织和性能的关系。研究结果表明:锻后空冷利用余热淬火时,较优淬火温度为750℃;淬火后自回火温度较高时,钢球芯部马氏体/下贝氏体复相组织中贝氏体组织含量较高且硬度较低,为了保证淬火后钢球具有高硬度及自回火的过程,则较优自回火温度为160℃;随着贝氏体等温转变时间的延长,贝氏体含量及冲击韧性显著提高,当贝氏体等温转变时间超过110 s时,硬度明显降低,即贝氏体较优等温转变时间为110 s。与常规淬回火相比,可得到钢球组织和性能的较优匹配,综合性能优于淬回火处理。

In this paper,the effects of quenching temperature,self tempering temperature and bainite isothermal transformation time on the hardness,impact toughness and microstructure of large diameter forged steel balls were studied,and the relationship between microstructure and properties of different heat treatment processes was compared and analyzed.The results show that the optimum quenching temperature is 750℃when the air cooling after forging is quenched by waste heat;When the self tempering temperature is higher after quenching,the content of bainite in martensite/lower bainite duplex structure in the core of steel ball is higher and the hardness is lower.In order to ensure the high hardness and self tempering process of steel ball after quenching,the optimal self tempering temperature is 160℃;With the extension of bainite isothermal transformation time,the bainite content and impact toughness increase significantly.When the bainite isothermal transformation time exceeds 110 s,the hardness decreases significantly,that is,the optimal bainite isothermal transformation time is 110 s.Compared with conventional quenching and tempering,this study can get the best match of microstructure and properties of steel ball,and the comprehensive properties are better than quenching and tempering.