Microstructure and mechanical properties of thixoformed GH4037 parts before and after heat treatment

In this work, the effect of heat treatment on the microstructure and high temperature mechanical properties of the GH4037 cylindrical parts fabricated via thixoforming was investigated. The microstructure of the thixoformed GH4037 parts before heat treatment was composed of solid grains and eutectic phases, while it mainly consisted of equiaxial grains after heat treatment. After heat treatment, a large number of spherical γ′ precipitates dispersed inside the grains, while primary γ′ particles, streaks of M₂₃C₆ carbides and blocks of MC carbides precipitated along the grain boundaries. When the tensile test temperature increased from room temperature to 1000 °C, the tensile strength of GH4037 alloy decreased gradually, while the elongation presented a trend of descending first and then ascending. After heat treatment, the tensile strength realized a remarkable improvement while the elongation was inevitably reduced. The results indicated that the microstructure and mechanical properties of the thixoformed GH4037 parts were significantly improved by heat treatment, and verified the feasibility of thixoforming in the field of nickel-based superalloys.