采用内耗法研究了两种马氏体热作模具钢在高温服役过程中的弹性模量及内耗特征,结合JMA方程探讨了时效前期的动力学过程。结果表明：620℃热稳保温过程中4Cr2Mo2W2MnV钢的软化主要以马氏体基体回复为主,而3Cr2W8V钢基体中大量的W、C脱溶及合金碳化物的沉淀,导致材料力学性能明显下降。4Cr2Mo2W2MnV钢在620℃工作温度下的热稳定性比传统热作模具钢3Cr2W8V好,主要是由于基体中的较多的Mn和相对稳定细小的Mo、V系MC型碳化物对马氏体热作模具钢的热稳定性有贡献作用。
Kinetics of thermal aging of two martenistic hot work tool steels were investigated by JMA equation and measurements of elastic modulus and internal friction.The results indicate that the recovery of martensite phase leads to the softening in 4Cr2Mo2W2MnV steel during the initial stage of high temperature aging.Desolution of W and V atoms from the matrix and precipitation of carbides result in the sharp decrease of mechanical properties of 3Cr2W8V steel aged at 620 ℃.The 4Cr2Mo2W2MnV steel has better thermal stability compared with 3Cr2W8V steel.Mn element and（Mo,V）C carbides in the matrix is responsible for the better thermal stability of 4Cr2Mo2W2MnV steel.
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