Shear-compression flow behavior and thermoforming properties of GH4169 superalloy

Abstract

Shear-compression deformation (SCD) is more proper than uniaxial compression to simulate the actual thermoforming with non-single strain modes. The flow behavior and thermoforming properties of GH4169 superalloy were studied by SCD at 1000–1200 ℃, 0.01–1 s−1. The flow curves showed significant fluctuation characteristics caused by the alternating dislocation proliferation and the dislocation annihilation. The slot region of shear-compression specimens (SCS) was most deformed, thus stress and strain drastically concentrated. The thermal activation energy of SCD was determined to be 556.5 KJ/mol, which was higher than that under uniaxial compression (411.0 KJ/mol). It’s indicated that the existence of shear strain increased the difficulty of thermoforming. Besides, the stress accumulation near the niobium-rich carbon-borides caused the severe instability cracking at 1200 ℃. In addition, virtually no change in size of the second phases during SCD except for 1100 ℃− 0.01 s−1. The fraction of deformation textures along the {110}, {111}, and {001} orientations decreased successively, indicating {110} was the prior orientation for grain rotating in SCD. Moreover, based on the processing map, the optimal SCD window was determined as 1135–1150 ℃ and 0.1–0.32 s−1 to guide the actual thermoforming of GH4169 superalloy.