5CrNiMo模具钢的热处理新工艺研究

Study on New Heat Treatment Technology of 5CrNiMo Die Steel

对深冷处理后的5CrNiMo模具钢进行了不同温度的回火处理,研究了100~600℃不同回火温度对钢组织、硬度、耐磨性及韧性的影响。结果表明在100~300℃低温回火处理时组织主要为粗大的片状马氏体,硬度较高但耐磨性较低,冲击韧性较差,断口中出现大面积的平整断裂面,脆性较高。当回火温度超过300℃时,组织发生转变,硬度有所降低,但耐磨性及冲击韧性明显提高;当回火温度为500℃时,粗大的片状马氏体消失,组织为细小的隐针状马氏体,耐磨性较高;当回火温度达到600℃时,组织主要为细小的粒状回火索氏体,同时冲击韧性达到峰值,断口中出现大量较小较深的断裂韧窝,硬度及耐磨性降低。深冷后500℃回火有利于提高5CrNiMo模具钢的综合力学性能。

Tempering treatment of 5CrNiMo die steel at different temperatures after cryogenic treatment was carried out. The influences of different tempering temperatures （100-600℃ ） on microstructure, hardness, wear resistance and toughness of the steel were studied. The results show that during low temperature tempering treatment （ 100 -300 ℃ ）, the microstructure is mainly coarse lamellar martensite, the hardness is higher, but the wear resistance and impact toughness are lower. A large area of the fiat fracture surface appears in the fracture, and the brittleness is higher. When the tempering temperature exceeds 300 ℃, the microstructure changes, the hardness decreases, but the wear resistance and impact toughness improve obviously. When tempering temperature is 500 ℃, coarse lamellar martensite disappears, the microstructure is fine acicular martensite and its wear resistance is higher. When the tempering temperature reaches 600 ℃, the microstructure mainly is small granular tempered sorbite, at the same time, the impact toughness reaches the peak. A large number of small and deep dimples appear in fracture, and the hardness and wear resistance decrease. The tempering at 500 ℃ after cryogenic is conducive to improve the comprehensive mechanical properties of 5CrNiMo die steel.