Effect of C content on microstructure and mechanical properties of GH4169 alloy

Abstract:

In order to investigate the effect of C content on microstructure and mechanical properties of GH4169 alloy, three kinds of GH4169 alloys were obtained by vacuum induction melting, homogenization heat treatment, forging and solid solution heat treatment. The precipitation behaviors of equilibrium precipitated phases of GH4169 alloy with different C content were investigated by thermodynamic calculation and differential scanning calorimetry. Combined with microstructure observation, X-ray diffraction phase analysis and tensile test at room temperature of alloys with different C content, the effect of C content on the tensile properties at room temperature and strain hardening exponent was analyzed. The results show that the increase of C content can promote the precipitation of MC carbide and M23C6 carbide. The amount of MC carbide enriched with Nb increases in linear with the increase of C content. The increase of C content can inhibit the precipitation of δ phase and has no significant influence on the precipitation of γ′ phase. With the increase of C content, the grain of solid-solution state is refined and the strength at room temperature is improved. The increase of C content will result in the decrease of elongation after fracture, strain hardening exponent and the capacity of uniform plastic deformation. MC carbide and its resulting void are the main factors to cause the fracture of the alloy at room temperature.