Crack elimination and mechanical performance enhancement of selective laser melted CM247LC superalloy

Nickel-based superalloy CM247LC is vital for aeroengines and gas turbines but suffers from severe cracking during selective laser melting (SLM), which severely limits its industrial application. In this study, a multi-approach coupled process optimization strategy was developed to modulate thermal gradients and mitigate stress accumulation, enabling the first successful fabrication of large-sized crack-free CM247LC by SLM. The resulting parts exhibit a refined nano-cellular substructure with a high dislocation density, which delivers outstanding mechanical properties with a yield strength of 1043.0 MPa, ultimate tensile strength of 1449.3 MPa and elongation of 13.0%—exceeding all previously reported values. This superior strength-plasticity synergy originates from the combined effects of cellular substructure strengthening and grain boundary strengthening, dislocation-precipitate interactions, and deformation-induced stacking faults. This work not only achieves a breakthrough in eliminating cracks in SLM of CM247LC but also elucidates the complicated processing-microstructure-property relationship, providing new insight into the additive manufacturing of hard-to-weld superalloys.