The softening of a hot-deformed die steel under thermocycling used in thermal fatigue tests is studied. The changes in the microstructure, in the dislocation structure and in the hardness of the surface layer and of the core of the thermocycled sample are analyzed. It is shown that the thermocycling process is accompanied by softening of the hot-deformed die steel, because the total concentration of structural flaws grows or decreases in turns at a general tendency to lowering.

中文翻译：

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热变形模具钢的热循环软化行为研究

研究了用于热疲劳试验的热变形模具钢在热循环下的软化。分析了热循环样品的微观结构、位错结构以及表面层和核心的硬度的变化。结果表明，热循环过程伴随着热变形模具钢的软化，因为结构缺陷的总浓度呈总体下降趋势，依次增加或减少。