Influence of laser powder bed fusion build orientation on the corrosion resistance of CoCrWMo alloy considering dislocation density character and lattice microstrain

This study investigates the impact of build orientation on the corrosion resistance of CoCrWMo alloys fabricated by Laser Powder Bed Fusion (L-PBF). Samples printed at angles from 0° to 90° were characterized using SEM, XRD (with modified Williamson-Hall and Warren-Averbach analysis), and potentiodynamic polarization in Ringer's solution. The results revealed that build orientation strongly affects microstrain, dislocation density, and dislocation character, which in turn govern passive layer composition and corrosion behavior. The sample printed at 90° exhibited the highest corrosion resistance, correlating with the lowest dislocation density, minimal microstrain, and the highest fraction of screw dislocations. XPS analysis showed this sample had the most Cr-rich passive layer, with Cr₂O₃ accounting for over 60% of oxide species. In contrast, low-angle samples exhibited more edge dislocations, higher microstrain, and less protective oxide films. These findings highlight the critical role of build-induced crystallographic anisotropy and defect structure in shaping corrosion response in L-PBF-processed biomedical alloys. The study also demonstrates the utility of advanced XRD-based methods for quantifying lattice distortions and dislocation populations. Importantly, the results support sustainable design strategies by enhancing corrosion resistance through process control, reducing reliance on coatings or alloying, and promoting resource-efficient manufacturing of biomedical and engineering components.