Recrystallization Behavior during Postprocessing of an Additively Manufactured Nickel-Based Superalloy

Abstract

Powder bed fusion–laser beam (PBF-LB) is a primary metal additive manufacturing (AM) process for industrialization. However, post-processing recipes for PBF-LB are distinct from those of conventional manufacturing and remain critical in governing the mechanical performance of PBF-LB components. This study investigates the influence of post-processing on the mechanical behaviour of Haynes 282—a Nickel-based superalloy utilized in turbine exhaust case and other high-temperature (up to 760 °C) applications—fabricated using high productivity themed PBF-LB with layer thickness of 60 and 90 μm. The as-built condition and recipe with solution treatment at 1150 °C (conventional treatment) exhibited anisotropy in both grain morphology and mechanical performance. Increasing the solution Treatment temperature to 1200 °C successfully reduced anisotropy in the 60 μm layer thickness build, owing to partial recrystallization, however anisotropy still exists in the 90 μm layer thickness build. Solution treatment at 1250 °C resulted in complete recrystallization and isotropic hot ductility across both the builds, albeit with a significant reduction in strength. These microstructural and mechanical response variations are discussed with emphasis on layer thickness, the volumetric energy density, dislocation density in the as-built microstructures, and solution treatment temperatures.