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析出硬化型热作模具钢2Cr3Mo2NiVSi(简称PH钢)在循环上限温度为650℃时,具有优良的热疲劳性能,循环上限温度为750℃时,热疲劳性能急剧下降。本文着重从PH钢在热疲劳中发生的组织变化,探讨热疲劳性能产生差异的原因,发现热疲劳后的组织变化主要表现在板条结构转变为位错胞或亚晶、碳化物粗化。循环上限温度不同时,PH钢在热疲劳中进行的回复再结晶程度显著不同,说明热稳定性是制约PH钢使用温度的一项重要性能指标。
Precipitation hardening hot work die steel 2Cr3Mo2NiVSi (referred to as PH steel) in the cycle of the maximum temperature of 650 ℃, has excellent thermal fatigue properties, the maximum temperature cycle of 750 ℃, the thermal fatigue properties of a sharp decline. This paper focuses on the microstructural changes of PH steel during thermal fatigue and explores the reasons for the difference in thermal fatigue properties. It is found that the microstructure changes after thermal fatigue are mainly manifested in the transformation of slab structure into dislocation cells or subgrains and carbide carburization. When the upper limit temperature is different, the degree of recovery recrystallization of PH steel during thermal fatigue is significantly different, which shows that thermal stability is an important performance index restricting the service temperature of PH steel.