Effect of solution treatment temperature on recrystallisation behaviour of Haynes 282 manufactured through laser powder bed fusion

Increasing layer thickness in Laser Powder Bed Fusion (PBF-LB) process of metals enable increasing productivity and facilitate industrialisation of metal additive manufacturing (AM) process. Understanding of microstructure in as-built stage and possible post-processing steps to modify the microstructure is critical for metal AM components. Haynes 282 Nickel based superalloy, typically used in aerospace and energy industries, was manufactured using PBF-LB process at 60 microns layer thickness. Two different solution treatment temperatures were studied to analyse the recrystallization behaviour of the as-built material. The as built microstructure consisted high dislocation density given the rapid cooling in PBF-LB process. Solution treatment at 1150°C resulted in reduced dislocation density but similar morphology to grains in as built condition with visible residual melt pool boundaries. Solution treatment at 1250°C resulted in recrystallised grain structure. The recrystallisation behaviour is discussed with relation to manufacturing process and kinetic behaviour of alloying elements.