42CrMo圆钢组织性能的优化

针对某钢厂生产的42CrMo小规格圆钢因硬度偏高，刀具损耗严重，给后续机械加工造成一定困难的问题，采用JMatPro软件计算了42CrMo 钢的CCT曲线和TTT曲线，在分析其微观组织转变规律的基础上，研究了控轧控冷工艺对产品组织、硬度的影响。结果表明，42CrMo圆钢终轧温度较高，冷速较快，冷却后圆钢组织为贝氏体是造成其硬度偏高的主要原因。因此，通过降低终轧温度，采用轧后水冷以及冷床使用保温罩等手段以有效降低轧后冷却速率的措施，将圆冷速控制到0.32 ℃/s，使42CrMo圆钢冷却后获得了铁素体+珠光体的组织，硬度控制在253~266HBW，满足了客户的使用要求。

Microstructure and properties optimization of 42CrMo round bar

Aiming at the problems of tool wear serious and difficulties in subsequent machining of small gauge 42CrMo steel round bar produced by a steel plant due to its high hardness,the CCT and TTT curves of 42CrMo steel were calculated using JMatPro software.Based on the analysis of its microstructure transformation law,the influence of controlled rolling and controlled cooling process on product microstructure and hardness was studied.The results show that the main reason of the higher hardness of 42CrMo round bar is the bainite microstructure of bar obtained by higher finishing rolling temperature and faster cooling rate.Therefore,some measures of reducing the finishing rolling temperature,adopting water cooling after rolling and using a heat preservation cover on the cooling bed to effectively reduce the cooling rate of round bar after rolling were applied,and its cooling rate was controlled to 0.32 ℃/s,the ferrite + pearlite structure was obtained,and the hardness was controlled at 253~266HBW,which met the requirements of customers.