Effect of Solution Treatment on the Microstructure and Elevated Temperature Tensile Properties of Forged Rene 41 Superalloy

The effects of a solution treatment on the microstructure and elevated mechanical properties of the forged Rene 41 superalloy were investigated. The results indicate that the solution treatment temperature has a significant influence on the γ' structure and mechanical properties. The sub-solvus solution treatment resulted in the co-existence of residual primary coarse γ' precipitates and fine secondary γ' precipitates, while the super-solvus solution treatments led to the complete dissolution of the primary γ' precipitates and the precipitation of a nano-sized secondary spherical γ' precipitate. The tensile strength increased and then decreased when the solution temperature increased from the sub-solvus to super-solvus solution treatments. In addition, the solution treatment time has a negligible influence on the γ' and overall mechanical properties due to the complete dissolution of γ' during the solution treatment at 1080 °C for 1 h. Moreover, the cooling rate following the solution treatment plays a significant role regarding the size and morphology of γ' and the mechanical properties. The secondary γ' changed gradually from spherical to concave cubic and octo-cubic and coarsened with the decrease in the cooling rate, resulting in an apparent decrease in strength and increase in ductility.