Correlation between Fracture Morphology and Microstructural Evolution during Long-Term Aging of EK61 Superalloy

Jin Huang; Guohua Xu; Heyong Qin; Lei Zheng

doi:10.1155/2020/1087024

Correlation between Fracture Morphology and Microstructural Evolution during Long-Term Aging of EK61 Superalloy

Scanning. 2020 Apr 23:2020:1087024. doi: 10.1155/2020/1087024. eCollection 2020.

Authors

Jin Huang^{1

2}, Guohua Xu², Heyong Qin², Lei Zheng¹

Affiliations

¹ School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
² High-Temperature Materials Department, China Iron & Steel Research Institute Group, Beijing 100081, China.

Abstract

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 γ' phase leads the reduction of the quantity of dimples, the chainization of carbides on grain boundaries leads to intergranular fracture, and the netting of η 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.