High γ’ Ni-base superalloys such as CM247LC processed via powder bed fusion – laser beam (PBF-LB) is characterised by high cracking susceptibility. The cracking can be broadly divided into hot cracking and solid-state cracking. Hot cracking occurs during the PBF-LB process, while solid-state cracking occurs during the first solutioning heat treatment. Hot cracking, in particular solidification cracking, can be minimized through tailoring alloy composition, process optimization and post-process heat treatment like hot isostatic pressing (HIP). However, strain age cracking (SAC) is a type of solid-state cracking that results in macro-cracks. Hence, it is crucial to perform solution heat treatment (and aging) to precipitate γ’ in the alloy without extensive cracking. Another challenge with CM247LC is creep performance as CM247LC processed by PBF-LB leads to a fine grain size and it is quite challenging to have increased recrystallization due to the small heat treatment window of CM247LC.

This study explores the utilization of hot isostatic pressing (HIP) to mitigate strain age cracking and enhance recrystallization in CM247LC processed by PBF-LB. Two distinct HIP strategies, both conducted above the γ' solvus temperature, were employed. Findings indicate that tailored HIP processing is promising in effectively reducing strain age cracking and enabling the successful heat treatment of this conventionally "non-weldable" Ni-base superalloy. The higher temperatures were found to lead to increased recrystallization which would ultimately lead to a better creep performance.