Effect of strain rate and high temperature on quasi-static and dynamic compressive behavior of forged GH5188 superalloy

Abstract

GH5188 Co-based superalloy is commonly employed in aero-engine eddy current and high-temperature components. Nonetheless, current research on its response behavior and mechanisms under dynamic and temperature loading remains scarce. Therefore, this study aims to investigate the dynamic compression and related deformation mechanism of GH5188 superalloy under the coupling effect of high temperature and strain rate. Quasi-static and dynamic compression tests were conducted on the forged GH5188 superalloy at both room temperature and 1000 °C. The results indicate that the material displays impressive yield strength and plasticity, while also showing a pronounced temperature sensitivity and strain rate hardening effect. Additionally, the dynamic stress-strain constitutive relationship of GH5188 is described by the modified J-C model. Regarding the dynamic deformation mechanism, GH5188 exhibited microbands, stacking faults, and nanotwins during high-strain rate compression. At 1000 °C, GH5188 underwent discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) at strain rates of 6000 s−1 and 10000 s−1, respectively. The synergistic effect of microbands and twinning enhanced the dynamic deformation ability and strengthening effect of the material. The transformation of microshear bands generated nanotwins. The twin boundaries are high-energy zones that can provide suitable recrystallization nucleation sites, induce dynamic recrystallization process, and thus obtain a fine and uniform equiaxed grain structure.