Overcoming Strain Age Cracking In An Additively Manufactured Non-Weldable Ni-Base Superalloy Through HIP

Paper in proceeding, 2024

Powder bed fusion - laser beam (PBF-LB) is an additive manufacturing technique that can produce near-net shape components. However, PBF-LB of high γ' Ni-base superalloys is limited due to their increased strain age cracking (SAC) susceptibility in post-processing heat treatment. This work proposes tailored hot isostatic pressing (HIP) to minimize SAC, in addition to studying the impact of solution temperatures above the γ' solvus on the microstructure. Results indicated that the Pre-pressurisation strategy where the target pressure was first achieved, and then the ramp up to the target temperature effectively minimized SAC. The microstructure study showed that there was recrystallization for temperatures as low as 1250°C, however, there was no significant change in the grain size (equivalent circle diameter was 80 to 90 μm) up to 1280 °C. These findings indicate that SAC can be minimized with HIP and with additional optimization can enable fully heat-treated crack-free components.