Precipitation and dissolution of δ and γ″ during heat treatment of a laser powder-bed fusion produced Ni-based superalloy

Abstract One drawback of the laser powder-bed fusion additive manufacturing (AM) technique is the build-up of residual stresses during processing that requires a stress-relief heat treatment prior to components being removed from the build plate. Here, we demonstrate the coprecipitation of the γ″-phase alongside the known δ-phase, during stress-relief annealing of AM Inconel 625 at 870 °C. The unexpected precipitation of γ″ in the AM material is attributed to the local solute enrichment to the interdendritic regions of the as-built solidification microstructure. Dissolution of the δ and γ″ phases is achieved after annealing for 15 min at 1150 °C.