变质处理后Fe-V-W-Mo-Cr合金热疲劳性能的研究

采用自约束热疲劳试验机对Fe-V-W-Mo-Cr合金进行了热疲劳试验，采用金相显微镜对热疲劳裂纹扩展行为进行了研究，同时用RE-Mg对Fe-V-W-Mo-Cr合金进行变质处理。结果表明，经RE—Mg变质处理后，碳化物和基体组织明显细化，并产生较多的小块状和颗粒状碳化物，促使合金的导热系数增加，热膨胀系数减小，热疲劳裂纹萌生所需热循环次数增加，裂纹扩展速率减小，在热循环700周次后的热疲劳裂纹长度减小约49％。

Study on the Thermal Fatigue Resistances of Fe-V-W-Mo-Cr Alloy Modified by RE-Mg

Thermal fatigue test of Fe-V-W-Mo-Cr alloy was examined on the self-strained thermal fatigue testing machines,and thermal fatigue crack propagation process was investigated by optical microscopy.At the same time Fe-V-W-Mo-Cr alloy was modified with rare earth elements(RE)-Mg.The results show that the carbides and matrix of cast Fe-V-W-Mo-Cr alloy modified by RE-Mg are refined,and many little lumps and grain carbides are produced as well.After modification,the heat conductivity coefficient of Fe-V-W-Mo-Cr alloy increases,while the heat expansion coefficient decreases.Moreover,the number of cycles needed by thermal fatigue crack initiation increases and the propagation rate of thermal fatigue crack decreases,after cycling 700 times the length of thermal fatigue crack decreases by about 49%.