Hot isostatic pressing temperature effects on the microstructure and mechanical properties of laser powder bed fusion-manufactured Hastelloy X

Hot isostatic pressing (HIP) of Hastelloy X alloy is an essential heat treatment process in manufacturing hot-end components for aerospace engines. This study investigated the microstructure evolution and mechanical properties of laser powder bed fusion-manufactured Hastelloy X superalloy at room and high temperatures under various HIP treatments. The results showed that as the HIP temperature increased, the recrystallization degree increased, with the proportion of low-angle grain boundaries decreasing from 49.7% at HIP1100 to 0% at HIP1210. The carbides along the grain boundaries evolved from particle distribution at HIP1100 to chain-like distribution at HIP1180 and coarsened at HIP1210. In the room temperature tensile test, specimens treated at HIP1100 exhibited the highest tensile strength due to restrained dislocation slip, grain refinement strengthening, and carbide dispersion strengthening. In the high-temperature tensile test, significant carbide coarsening was induced at HIP1100, while minimal changes were observed at HIP1180 and HIP1210. As the HIP temperature increased, the tensile strength and elongation both improved due to the synergistic effect of the reduced number of grain boundaries and chain-like distribution of carbides. The cracks primarily propagated along the grain boundaries, with the HIP1210 specimen showing a better capacity for crack inhibition.