热处理对高Cr冷作模具钢组织和力学性能的影响研究

Effect of Heat Treatment on Microstructure and Mechanical Properties of High Cr Cold Working Die Steel

采用箱式电阻炉对铸态高Cr冷作模具钢进行了不同温度的高温处理,并对热处理试样显微组织进行了观察,对拉伸、硬度等力学性能进行了检测。结果表明,随着处理温度的升高,试验钢球化退火后组织中碳化物颗粒先逐渐粗化,1170℃后又明显细化,网状共晶渗碳体含量逐渐减少,1170℃时其含量降低至8%左右,基本消除对基体割裂的影响;回火组织主要由回火马氏体和未溶碳化物组成,1150℃以上处理的试验钢回火组织中还出现少量残余奥氏体;随处理温度的提高,试验钢伸长率先升高,1150℃处理时伸长率有所下降,1170℃处理时升高达到最大值,抗拉强度和硬度的变化趋势基本一致,均是先逐渐下降,至1170℃处理时又有所升高。

The different high temperature treatment of as cast high Cr cold working die steel was carried out by using the chamber electric furnace. Microstructure of heat treated samples was observed, And mechanical properties such as tensile and hardness were measured. The results show that, with the increase of treatment temperature, the carbide particles in the microstructure of the test steel after spheroidizing annealing are gradually coarsened firstly and then refined obviously at 1170℃, and network eutccfic cemenfite content gradually reduces. Its content reduced to about 8% when treatment is at 1170 ℃, and the influence on matrix division is basically eliminated. The temper microstructure is mainly composed of tempered martensite and undissolved carbides. A small amount of residual austenite in the temper microstructure appears when the treatment of the test steel is above 1150 ℃. With the increase of treatment temperature, the elongation increases firstly and then declines when the treatment is at 1150℃, and it reaches the maximum when the treatment is at 1170℃. The change tendency of tensile strength and hardness is basically the same, which both decreases gradually and then increases when the treatment is at 1170℃.