Effect of heat treatment on microstructural and high-temperature mechanical performance of additively manufactured Ni-based GH4099 superalloy

A systematic investigation was conducted into the infiuence of thermal treatment on the microstructure evolution and mechanical properties of additively manufactured Ni-based GH4099 superalloy, with specific focus on the selective laser melting (SLM) fabrication process. The as-fabricated GH4099 alloy demonstrated characteristic columnar grain structures with pronounced residual stresses, predominantly attributed to the steep thermal gradients inherent in the SLM process. Through solution treatment at 1110 ℃, a significant microstructural transformation was observed, characterized by recrystallization that converted the columnar grains into equiaxed structures while effectively mitigating residual stresses. Concurrently, this treatment facilitated the precipitation of fine γ’ phases, thereby enhancing the material’s strength. Subsequent aging treatments at 800 and 900 ℃, however, led to γ’ phase coarsening, which diminished the precipitation strengthening effect, but concurrently improved the alloy’s plasticity. These findings highlight the pivotal role of thermal processing in optimizing the strength-ductility balance for SLM-manufactured superalloys under high-temperature service conditions. This work contributes to a comprehensive understanding of the microstructure-property relationships in thermally processed SLM GH4099 superalloy, providing critical insights for the development of advanced Ni-based superalloys and contributing to the refinement of SLM manufacturing protocols for high-performance applications.