Huang Jin, Xu Guohua, Qin Heyong, Zheng Lei
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
High-Temperature Materials Department, China Iron & Steel Research Institute Group, Beijing 100081, China.
Scanning. 2020 Apr 23;2020:1087024. doi: 10.1155/2020/1087024. eCollection 2020.
Microstructural evolutions of EK61 superalloy during long-term aging until 1000 h at 700°C and 750°C, respectively, are studied by combination of Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Impact fracture morphologies after aging for different time are observed by the SEM. The microstructure is found to be relatively stable during aging at 700°C, and the fracture morphologies are characterized by transgranular fracture. At 750°C, the coarsening of ' phase leads the reduction of the quantity of dimples, the chainization of carbides on grain boundaries leads to intergranular fracture, and the netting of phases within grains leads to the formation of lamellar cleavage steps. It is obvious that the destabilization of precipitated phases affects fracture morphology significantly. The relationship between fracture morphology and the microstructure promotes the evaluation of service reliability of EK61 superalloy.
通过扫描电子显微镜（SEM）和透射电子显微镜（TEM）相结合的方法，研究了EK61高温合金分别在700°C和750°C下长期时效直至1000小时的微观结构演变。通过SEM观察了不同时效时间后的冲击断口形貌。发现在700°C时效期间微观结构相对稳定，断口形貌以穿晶断裂为特征。在750°C时，'相的粗化导致韧窝数量减少，晶界碳化物的链化导致沿晶断裂，晶粒内相的网络化导致片状解理台阶的形成。显然，析出相的失稳对断口形貌有显著影响。断口形貌与微观结构之间的关系有助于评估EK61高温合金的服役可靠性。
