Processing Strategy for Reinforcing Ti6Al4V Alloy Using Laser Powder Bed Fusion

Laser Powder Bed Fusion (LPBF) is an advanced additive manufacturing technique widely used to produce complex metallic structures. While previous research has largely examined microstructural evolution in LPBF materials, linking laser melting and cooling conditions to grain morphology and mechanical behavior, this study explores how intentionally varying cooling rates through a layer-by-layer, localized secondary thermal processing strategy affects Ti6Al4V. The work evaluates resulting changes in microstructure, defect formation, and grain size, as well as key mechanical metrics such as hardness and fracture toughness. Introducing a controlled, localized secondary laser exposure within each layer produced significant microstructural modification, leading to spatial variations in grain size and hardness of up to 10% across the build. This approach also increased crack-arresting capability by more than 30%. Collectively, these results highlight the promise of local secondary laser processing as a powerful tool for tailoring spatially varying properties in LPBF components, enabling the design of additively manufactured materials with site-specific performance characteristics.