IN738LC 镍基高温合金高温蠕变疲劳性能研究

Interaction between Creep and Fatigue for a Nickel Base Superalloy IN738LC at Elevated Temperature

在对ＩＮ７３８ＬＣ合金的含保载低周疲劳试验中发现，蠕变变形的增加导致了疲劳寿命的降低。在对试样的微观检验中未见有典型的晶界孔洞型蠕变损伤，而多见的是碳化物及晶界的氧化。所有的裂纹都在试样表面萌生并沿着晶界扩展，因此，在蠕变载荷下晶界氧化是一种可能的蠕变损伤。这里运用Ｄａｎｚｅｒ关系讨论了损伤的机理，并对实验结果进行了较理想的解释。

The creepfatigue property of nickel base superalloy IN738LC was investigated at elevated temperature It was observed that the cyclic life (number of cycle to failure) decreases with the increase of creep deformation The microscopical examination didn′t show the typical creep damage in form of porosity formed at grain boundaries Instead, carbide oxidation and grain boundary oxidation on the specimen surface were frequently observed All cracks were formed on the specimen surface and propagated along the grain boundaries Therefore, the oxidation of grain boundaries under creep load is a possible creep damage In this work a damage mechanism was discussed with the DanzerRelation It can explain the decrease of cyclic life in creepfatigue tests well