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本文用金相表面观察及断口金相分析的方法得到铁镍基高温合金疲劳裂纹萌生在孪晶与基体界面、夹杂物(碳氮化钛)与基体界面以及表面或内部疏松夹渣等冶金缺陷上的实验证据。用扫描电镜及透射电镜观察了大量的这类合金高周、低周疲劳断口,特别对铸造镍基高温合金第一阶段断口进行了细致的观察,讨论了第一阶段疲劳断口的形成机制、性质,并总结了镍基合金第一阶段断口与体心立方金属解理断口的差别,依据一种铸造镍基合金不同应力、温度、试样形状等条件下疲劳断口的特征时影响第一阶段疲劳裂纹扩展的因素进行了分析。
In this paper, metallurgical surface observation and fracture surface metallographic analysis were used to obtain the fatigue crack initiation of the Fe-Ni-based superalloy at the interface between the twin and the matrix, the interface between the inclusions (titanium carbonitride) and the matrix, the loose inclusions on the surface or inside, On the experimental evidence. A large number of high-cycle and low-cycle fatigue fractures were observed by SEM and TEM. In particular, the first-stage fracture of cast nickel-base superalloy was observed carefully. The formation mechanism of the first-stage fatigue fracture, properties , And summarized the difference between the first stage fracture and the body-centered cubic fracture cleavage of Ni-based alloy. The first stage fatigue was affected by the characteristics of fatigue fracture under different conditions of stress, temperature and specimen shape of the cast Ni-base alloy The factors of crack propagation were analyzed.