Effect of Microstructural Evolution on Plasticity of GH4065A Superalloy Cast Ingot During Homogenization Hot Treatment

Improved plasticity in superalloy castings minimizes processing defects, reduces stress concentration, and enhances mechanical performance. To obtain the microstructure–plasticity relationship, GH4065A ingots were homogenized at 1140–1200 °C for 5–80 h. Microstructural analysis tracked the evolution of dendritic crystals and precipitates (including η phase, carbides, and borides). Tensile tests were conducted to assess plasticity in terms of elongation and reduction in area. Results show that increasing temperature accelerated dendritic dissolution. While 1140 °C was ineffective for short-term dendrite elimination, temperatures of 1160–1200 °C achieved near-complete dissolution within 30–60 h. Precipitates evolution was also observed: the η phase dissolved preferentially, while the sizes of carbides and borides gradually decreased, especially at 1200 °C. Electron probe microanalysis confirmed Nb as the most segregated element. With higher temperatures, Nb diffused from microsegregated zones toward homogeneity. Plasticity improved notably when the Nb segregation coefficient was ~1.5 but decreased at ~1. The optimal homogenization parameters were determined as 1180 °C for 15–60 h. This study provides key processing guidelines for GH4065A ingots, supporting enhanced service performance and operational safety of related components.