Study on Hot Deformation Behavior and Processing Maps of Cobalt‐Based Superalloy GH5188

Abstract

True stress–strain data are obtained through the thermal compression test of the cobalt‐based superalloy GH5188 at the temperature range of 1080–1180 °C and the strain rate of 0.1–10 s−1, and the Arrhenius constitutive equation considering the effects of temperature, strain rate, and strain is established. The microscopic deformation mechanism and the appropriate process range are proposed based on the analysis of the dynamic material model and electron backscattered diffraction (EBSD). The results show that the established constitutive equation exhibits predictive ability, and the calculated thermal activation energy Q value is 446.1054 KJ mol−1; when the strain is 0.7, the GH5188 superalloy undergoes dynamic recrystallization (DRX) at 1130 °C in the form of discontinuous DRX; when the temperature is 1180 °C, the degree of DRX is significantly improved, and evenly distributed equiaxed grains are obtained; when the strain is 0.2, 0.4, and 0.6, DRX is mainly affected by the degree of deformation, and its occurrence is accompanied by the generation of Σ3. Combined with the analysis of the processing maps and EBSD diagrams, the optimal thermal deformation parameters of GH5188 alloy are determined as follows: the strain is 0.7, the deformation temperature is about 1180 °C, and the strain rate is about 1 s−1.