Effect of selective rescanning parameters on PBF-LB/M Ti-6Al-4 V parts

Rescanning has emerged as a promising strategy in laser powder bed fusion (PBF-LB/M) for tailoring the microstructure and properties of metal components. However, previous studies have mainly focused on rescanning entire layer or multiple layers, which increases processing time and cost. In this study, we investigate a lattice-based selective rescanning strategy with varying process parameters and its effects on the microstructure, mechanical properties, and corrosion resistance of PBF-LB/M Ti-6Al-4 V samples. Only the lattice regions were rescanned by reducing either laser power, scan speed, or hatch distance to 50% of the values used in optimally processed base material. The density, porosity, martensitic phase, microhardness, and electrochemical properties of the rescanned specimens were compared with those of non-rescanned reference sample. Reduction in laser power improved both density and corrosion resistance, while reduced scan speed and hatch distance induced keyhole porosity. Distinct variation in hardness between rescanned and non-rescanned regions was observed. This research demonstrates that a localized rescanning approach can effectively tailor the martensitic phase to simultaneously enhance hardness and corrosion resistance in Ti-6Al-4 V specimens, offering a time-efficient alternative to conventional global rescanning techniques.