Impact of Hot Isostatic Pressing on Microstructure Evolution and Creep Performance of Powder Bed Fusion–Laser Beam Processed CM247LC

Journal article, 2025

Superalloys manufactured through powder bed fusion–laser beam (PBF-LB) are known to suffer from poor creep performance due to their fine and anisotropic microstructures and unoptimized heat treatments. This study investigates the impact of a combined hot isostatic pressing (HIP) and solution heat treatment on the microstructure and creep behavior of the non-weldable Ni-base superalloy CM247LC manufactured via PBF-LB. HIP treatments were conducted at 1250 °C and 1280 °C, and 200 MPa pressure to optimize grain structure and obtain favorable grain boundary decorations. Microstructural characterization revealed that HIP at 1280 °C resulted in a more homogenous grain size distribution with a higher fraction of grains between 100−200 μm, indicative of enhanced recrystallization and grain growth. Subsequent creep testing demonstrated a 23% improvement in creep life for the HIP at 1280 °C. This enhanced performance is attributed to a combination of factors, including improved γ′ solutioning and beneficial grain boundary decoration (M2B borides). These findings highlight the critical role of tailored heat treatments, particularly HIP parameters, in optimizing the microstructure and consequently the high-temperature creep resistance of PBF-LB-processed superalloys.