摘要
研究了返回料添加比例对新型抗热腐蚀高温合金K 44热疲劳性能的影响。结果表明:新料和返回料合金试样V型缺口尖端主裂纹扩展长度与热循环次数之间遵循L=bNa规律。新料合金热疲劳裂纹萌生和扩展速率最低,随着合金中返回料比例的增大,热疲劳裂纹萌生速率和扩展速率也增大。热疲劳裂纹萌生于V型缺口尖端附近区域,沿枝晶间、晶界和开裂的碳化物扩展,主裂纹扩展以裂纹尖端连续开裂的形式进行。返回料合金由于氮含量增加导致共晶和夹杂物增多,碳化物聚集块化,加速了热疲劳裂纹的萌生与扩展。合金经热疲劳实验后,裂纹两侧产生氧化带和γ′相贫化带。
The thermal fatigue test was conctucteo on a new corrosion-resistant K44 superalloy with different revert proportion. The results showed that the relationship between length of main crack and thermal cycle index could be described as L = bN^a for both virgin and revert alloys. The crack initiation rate and crack propagation rate of virgin alloy was the lowest. With the increase of revert proportion, the crack initiation rate and crack propagation rate increased. Thermal fatigue cracks initiated near the Ⅴ-type notch tip, propagated mainly along interdendritic zones, grain boundaries or splitting carbides. The main crack grew with continual splitting of the crack tip. The high content of nitrogen and oxygen in revert alloy induced the increment of （γ＋γ^-1） eutectics and inclusions and the agglomeration of carbides, which accordingly accelerated the initiation and propagation of the thermal fatigue crack. Oxide and γ^-1 depleted areas existed on both sides of thermal fatigue crack.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2005年第8期24-27,共4页
Journal of Materials Engineering
