新型刀具用钢的热处理工艺及微观组织

Heat treatment process and microstructure of a new SIMR tool steel

采用不同淬回火工艺系统地研究了一种高碳高铬马氏体刀具用钢—SIMR的热处理工艺和微观组织,通过XRD、SEM和TEM等表征方法,分析测试了不同淬火温度和回火温度下SIMR刀具用钢的微观组织、碳化物形貌与分布和显微硬度等,获得了SIMR的最佳热处理工艺。结果表明,SIMR刀具用钢的晶粒尺寸随着淬火温度的升高而逐渐增大,冶炼凝固过程中析出的富铬M7C3型一次碳化物随着淬火温度的提高而逐渐回溶,显微硬度总体上呈现先升高后降低的趋势,回火温度在150~300℃间,SIMR刀具用钢的最佳热处理工艺为在1050℃淬火处理20 min,油冷,然后在150℃回火处理90 min,空冷。

The heat treatment process and microstructure of the SIMR,a high carbon and high chromium martensitic tool steel,were systematically studied by different quenching and tempering processes. Microstructure,morphologies and distribution of carbides and microhardness of the SIMR tool steel were researched by means of XRD,SEM,and TEM characterization methods,and the optimum heat treatment of the SIMR tool steel was obtained. The tested results show that the grain size of the SIMR tool steel gradually grows with the increase of quenching temperature,and the chromium-rich M7 C3 type primary carbide which forms during the smelting solidification process,gradually re-dissolves with the increase of quenching temperature,and the micro-hardness increases first and then decreases. When the tempering temperature is between 150 ℃ and 300 ℃,the optimum heat treatment process for the SIMR tool steel is quenching at 1050 ℃ for20 min,and then oil quenching,finally tempering at 150 ℃ for 90 min and then air cooling.