返回料循环使用次数对K465合金热疲劳性能的影响

Effect of revert recycle times on thermal fatigue property of K465 alloy

采用逐次添加的方式研究返回料循环使用次数(简称返回次数)对K465合金(返回料∶新料=1∶1)热疲劳性能的影响。研究发现:含返回料合金的热疲劳裂纹长度与热疲劳循环次数之间遵循L=b Na规律;氧含量是影响合金热疲劳性能的重要因素,在同等氧含量的情况下,合金的抗热疲劳性能随返回次数的增加而降低;含返回料合金的热疲劳裂纹的萌生、扩展与新料不同,其裂纹是在块状碳化物或疏松处萌生,并沿着枝晶间、晶界、开裂的碳化物及碳化物与基体的界面扩展。

The effect of revert recycle times on the thermal fatigue property of K465 superalloy was investigated by a stepwise addition method with 1∶1 weight ratio of revert alloy to fresh alloy. The results reveal that the relationship between the crack length and the thermal cycle times for the K465 alloy with revert alloy coincides with the formula L=b Na. Oxygen content is the important factor influencing the thermal fatigue property of K465 alloy. For similar oxygen content,the thermal fatigue resistance of K465 alloy decreases with the increase of revert recycle times. The thermal fatigue crack initiation and propagation of K465 alloy with revert alloy differ from that of fresh K465 alloy. The thermal fatigue cracks initiate from the block-like carbides or micro-porosities,and propagate mainly along interdendritic zones,grain boundaries,splitting carbides or boundaries between carbides and matrix.