Cracking suppression in powder bed fusion-laser beam of CM247LC Ni-based superalloy

• Achieved virtually crack-free (0.04 mm/mm 2 ) CM247LC without preheating. • Unidirectional scanning yields a twofold smoother surface finish (Ra = 7.39 µm). • 10 × 10 mm 2 island size lowers bulk cooling rate by ∼3×, mitigating thermal stress. • Optimised strategy shifts grain boundaries from HAGBs to LAGBs (<15°). • Strong <0 0 1> texture (11.9 MUD) correlates with reduced cracking susceptibility. High γ′ Ni-based superalloys, such as CM247LC studied here, suffer from a high propensity for crack formation during additive manufacturing, hampering mission-critical applications due to poor weldability. In this work, crack suppression was achieved in CM247LC processed via Powder Bed Fusion-Laser Beam (PBF-LB) through systematic control of scanning strategies. Without compositional modification or substrate preheating, cracking density was reduced from 3.14 mm/mm 2 in the default sample to a virtually crack-free microstructure of 0.04 mm/mm 2 in the optimised sample. A twofold enhancement in surface finish was also achieved by employing a unidirectional scanning strategy, which avoids laser turn-around-induced heat accumulation and thermal stresses. The optimal strategy was designed based upon a systematic evaluation of island size, shift, rotation angle, and meander, with their impact on heat input and cooling rates rationalised using a transient finite volume temperature field simulation. The thermal model reveals that increasing island size promotes higher heat retention and lower thermal gradients, significantly mitigating cracking susceptibility. The ratio of active to inactive laser scan times was identified as a key descriptor governing crack reduction. Our work suggests that tuning scanning strategies offers a promising alternative to alloy redesign or preheating for processing crack-susceptible Ni-based superalloy CM247LC via PBF-LB