Tensile properties and deformation mechanisms of a solution treated Ni–Fe-based alloy at high temperatures

Abstract

This study investigated the high-temperature tensile properties and deformation mechanisms of a solution treated Ni–Fe-based alloy ranging from 600 to 750 °C. The solution treated GH4070P (HT700P) alloy exhibits superior yield strength of 490 MPa and ultimate strength of 593 MPa at 700 °C. The major carbides in the alloy are the blocky MC and discrete-distributed M23C6. The MC and M23C6 carbides at the grain boundaries (GBs) can impede crack propagation, yet concurrently intensify the stress concentration. The transgranular and intergranular fractures are observed. Above 700 °C, micro-cracks emerge around M23C6 carbides at GBs and then are interlinked to form lengthy secondary micro-cracks, resulting in the intergranular fracture. The precipitation of γ′ precipitates during tension at 700 and 750 °C confers the alloy to a higher strength.