Optimizing the comprehensive properties of PBF-LB/M Ti6Al4V alloy in nitric acid by heat treatment

Abstract

Abstract Titanium (Ti) alloys fabricated by laser powder bed fusion (PBF-LB/M) exhibit substantial potential for industrial applications due to their good formability and cost-effectiveness. However, the poor matching between strength, plasticity, and corrosion resistance properties in as-fabricated PBF-LB/M Ti-alloys hinders their broader application. Herein, the effect of heat treatment on the comprehensive properties of PBF-LB/M Ti6Al4V alloy was investigated. Results revealed that hot isostatic pressing (HIP) and annealing treatment (AT) facilitate the transformation of acicular αʹ-Ti phase to α + β phase, leading to a shift in the fracture mechanism from brittle to ductile behaviour, thereby improving the strength-plasticity balance. Moreover, HIP effectively reduced internal defects and promoted the formation of a denser, more robust passive film in nitric acid, compared to PBF-LB/M alloy after AT. This enhanced passive film imparts superior corrosion resistance, thus achieving a favourable compromise between strength, plasticity, and corrosion resistance in PBF-LB/M Ti6Al4V alloy.