Laser powder bed fusion of NiTi: effect of laser power and scanning speed on phase transformation temperatures

Despite the growing use of powder bed fusion laser beam in metals (PBF-LB/M) to fabricate NiTi shape memory alloys, the interplay between process parameters and functional performance remains poorly understood, hindered by small-scale studies that fail to capture parametric complexity. This work presents a comprehensive analysis of over 200 NiTi samples, systematically varying laser power and scanning speed to uncover their effects on phase transformation behaviour. It is demonstrated that energy density, a widely assumed predictor, inadequately explains transformation temperatures, which instead exhibit a nonlinear dependence on both laser power and scanning speed, yet align linearly with scanning speed at fixed power. These findings challenge conventional assumptions and provide a robust framework for tuning PBF-LB/M parameters to achieve consistent, application-ready NiTi components, advancing the reliability of shape memory alloys in critical engineering and biomedical applications.