热处理对高Cr热作模具钢组织和力学性能的影响

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

通过中频真空感应炉冶炼了试验钢,采用箱式电阻炉进行了热处理试验,并分析了预处理、淬火、回火等不同热处理下的组织、硬度变化规律,探讨了淬火温度对试验钢最终组织和力学性能的影响。结果表明,试验钢预处理后的组织为高温回火马氏体+弥散的第二相,组织均匀细化,晶界连续的网状组织完全消除。淬火组织为板条马氏体+残余奥氏体,硬度较高;回火组织主要为回火马氏体+少量残余奥氏体,马氏体板条较为明显,硬度下降。随淬火温度提高,回火组织中回火马氏体板条更为细小化,残余奥氏体含量略有增加;试验钢淬火态、回火态硬度均提高;冲击功先略有降低,当淬火温度超过1040℃时又提高。

The test steel was melted by medium fi＇equency vacuum induction furnace. Heat treatment experiment was carried out using a box type resistance furnace. The changes of microstructure and hardness under different heat treatment, such as pretreatment, quenching and tempering, were analyzed. The effect of quenching temperature on the fmal microstructure and mechanical properties of the test steel was discussed. The results show that, after pertreatment the microstructure of the test steel is the high temperature tempered martensite and the disperse second phase, the microstructure is fine and uniform, and the continuous network microstructure on grain boundary is completely eliminated. The quenching microstructure is martensite and residual austenite, and the hardness is higher; the tempering microstructure is mainly tempered martensite＋a small amount of residual austenite, martensite lath is more obvious, and the hardness decreases. With the increase of quenching temperature, tempering martensite lath in the microstructure is finer, and residual austenite content increases slightly; the hardness of quenched and tempered test steel is increased. Impact power first slightly reduces, while it increases when the quenching temperature is above 1040 ℃.