模具钢堆焊金属的强度与变形对热疲劳抗力的影响

对两种模具钢堆焊金属（3Cr2W8和HM3）进行了外加约Coffin型热疲劳试验。试验表明，模具堆焊金属的热疲劳抗力由其变形的难易程度决定：变形越困难，热疲劳抗力越高。研究进一步表明，材料变形的难易程度又与变温循环过程，热疲劳试样拉伸应力的增加和材料屈服强度的降低有关。屈服强度的降低是由于在循环过程中，材料的组织发生了动态变化，如动态回复、动态再结晶及第二相粒子的析出与聚集；拉伸应力的增加是由于微观组织中应力松弛的结果。

Effect of Strength and Deformation of Die Steel Deposited Metal on Thermal Fatigue Resistance

The external constraint test of the coffin model for two kinds of deposited metals, called the 3Cr2W8 and HM3, is conducted. It is concluded that the thermal fatigue resistance closely relates to the deformation resistance. The more difficult the deformation is, the higher the thermal fatigue resistance is. Moreover, it is revealed that the deformation resistance in the thermal cycle process is related to the increase of its tensile stress and the decrease of yield strength. Investigation shows that the decrease of the yield strength is due to the dynamic evolution of micro-structures, such as its dynamic recovery, dynamic recrystallization and the second phase particle precipitation and concentration. And the increase of the tensile strength is caused by the stress release of the microstructure for changing.