Abstract: The effects of Quenching-Tempering-Austempering （QTA） duplex phase heat treatment process （Q 1 030 ℃， 30 min； T 520 ℃， 2 h； A 250 ℃， 3 h） at different prequenching temperatures on the microstructure， mechanical properties and the friction and wear properties of cold working die steel DC53 were investigated and the results were compared with those of the conventional Quenching-Tempering （QT） heat treatment process （Q 1 030 ℃， 30 min； T 520 ℃， 2 h）. The results show that the microstructure obtained by QT process is mainly tempered martensite and the microstructure mainly composing Lower Bainite/Martensite （LB/M） duplex phase can be resulted from the QTA process. The strength reduction due to the LB and the retained austenite （A_R） can be partly offset by the grain refinement strengthening from the refinement of original austenite grain by duplex phases， and the impact toughness of DC53 can be greatly improved by this complex microstructure. Compared with the mechanical properties of the QT process， the hardness of the QTA at prequenching temperature 100 ℃ is only 1.4 HRC lower but the impact absorption energy is 2.44 times higher. Therefore， superior combination of strength and toughness can be obtained by the QTA process.

Key words: Cold Working Die Steel, DC53, Heat Treatment, Microstructure, Mechanical Property

摘要： 本文研究了不同预淬火温度的QTA（Quenching-Tempering-Austempering）复相热处理工艺（Q为1 030 ℃，30 min；T为520 ℃，2 h；A为250 ℃，3 h）对冷作模具钢DC53的微观组织和力学性能及摩擦磨损性能的影响，并与常规淬火-回火（Quenching-Tempering，QT）热处理工艺（Q为1 030 ℃，30 min；T为520 ℃，2 h）进行对比。结果表明，QT工艺得到的组织以回火马氏体为主；QTA工艺可以得到下贝氏体/马氏体（Lower Bainite/ Martensite，LB/M）为主的复相组织，这些复相对原奥氏体晶粒的分割产生的细晶强化作用部分抵消了LB和残余奥氏体（A_R）的弱化作用，并且，这些复杂的微观组织极大提升了DC53钢的冲击韧性；当QTA的预淬温度为100 ℃时，其硬度仅比QT工艺低1.4HRC，但是冲击吸收能量却是QT工艺的2.44倍。因此，优化的QTA工艺可以得到较高的强韧综合性能。

关键词: 冷作模具钢, DC53, 热处理, 微观组织, 力学性能