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采用自约束热疲劳试验方法,并结合变倍体视显微镜、MH-3型数显式显微硬度计及热疲劳损伤因子计算机辅助分析软件研究了三种芯棒用合金钢的热疲劳性能。分析了其热疲劳裂纹的萌生、扩展与材料韧性之间的关系。结果表明,TBX-1钢和TBX-4钢的热疲劳裂纹萌生在循环次数为400次左右,裂纹萌生较H13钢早;循环3000次后,TBX-4钢表现出良好的热疲劳性能,疲劳损伤因子明显低于TBX-1钢和H13钢,热疲劳抗力优于TBX-1钢和H13钢。分析了这三种钢的热疲劳机制,指出决定材料热疲劳裂纹抗力的关键因素是钢的冲击韧性。
Thermal fatigue properties of the three kinds of alloyed mandrel bars were studied by self-restraining thermal fatigue test combined with variable magnification stereo microscope, MH-3 digital explicit microhardness tester and thermal fatigue damage factor computer-aided analysis software. The relationship between thermal fatigue crack initiation and propagation and material toughness was analyzed. The results show that the thermal fatigue crack initiation of TBX-1 steel and TBX-4 steel is about 400 times and the initiation of cracks is earlier than that of H13 steel. After 3000 cycles, TBX-4 steel shows good thermal fatigue and fatigue The damage factor is obviously lower than that of TBX-1 and H13 steel, and the thermal fatigue resistance is better than that of TBX-1 and H13 steel. The thermal fatigue mechanism of these three kinds of steels is analyzed, and the key factor that determines the thermal fatigue cracking resistance of the material is the impact toughness of the steel.