采用自约束热疲劳试验法,研究了新型热作模具钢在热疲劳裂纹萌生阶段施加脉冲电流处理后的热疲劳裂纹扩展情况。结果表明:在热疲劳裂纹萌生的不同时机施加脉冲电流,对热疲劳裂纹扩展的影响效果存在明显差别。其中在热疲劳初始循环300次后再施加脉冲电流,效果较为显著,此时热疲劳裂纹细小,且均匀,裂纹扩展的速度较慢,横截面的显微硬度梯度下降也较慢。 Self-restrained thermal fatigue test was used to study the thermal fatigue crack propagation of the new hot die steel during the thermal fatigue crack initiation with pulse current. The results show that there are significant differences in the effect of thermal fatigue crack propagation when pulse current is applied at different timing of thermal fatigue crack initiation. Among them, the pulse current was applied 300 times after the initial thermal fatigue cycle, and the effect was more obvious. At this time, the thermal fatigue crack was small and uniform, the crack growth rate was slower, and the cross-section microhardness gradient decreased slowly.