Development of a hot-cracking-free Ni-based superalloy for laser powder bed fusion via composition optimization

Hot cracking has remained a significant challenge that hinders the broader application of laser powder bed fusion (LPBF)-fabricated Ni-based superalloys. In this study, the chemical composition of TMSL-1-a proprietary alloy prone to hot crack, was systematically optimized to develop a novel hot-crack-free alloy, TMSL-2. The alloy was designed to account for both the solidification behavior and phase-transformation stress during the LPBF cyclic process. Two criteria, the solidification cracking index (SCI) and the strain-age cracking (SAC) criterion, were used to guide the optimization. As a result, TMSL-2 demonstrated hot-cracking-free fabrication across a wide range of LPBF parameters. In addition to its excellent printability, the as-printed alloy exhibited superior mechanical performance, achieving an ultimate tensile strength of 1195 MPa and an elongation of 35.1 % at room temperature. Furthermore, the combined use of the SCI and the SAC offers an effective evaluation index for assessing hot-cracking susceptibility in LPBF-processed Ni-based superalloys. This work offers a practical composition optimization route for designing hot-cracking-resistant Ni-based superalloys for additive manufacturing.