Effect of process parameters on mechanical properties and corrosion resistance of Ti–6Al–4V alloys prepared by selective laser melting

Titanium alloys fabricated through additive manufacturing have garnered widespread attention in biomedical field, with their excellent mechanical and corrosion resistance properties serving as the prerequisites for such applications. This study thus investigates the influence of selective laser melting (SLM) process on the mechanical properties and corrosion resistance of Ti–6Al–4V (TC4) alloys. Results show that the microstructure of the prepared TC4 alloys is mainly composed of columnar β grains growing along the building direction and fine acicular α′ martensite within them. Alloy printed at low power (150 W) and high speed (1300 mm/s) exhibits weakened plasticity and corrosion resistance due to un-melted gaps and micro-void defects. Alloys prepared at medium power (200 W) show stable mechanical properties; however, their corrosion resistance fluctuates significantly with prolonged immersion time due to uneven formation rate and poor stability of the passivation film. Whereas, alloy printed at high power (250 W) and medium speed (1200 mm/s) demonstrates regularly grown columnar β grains and dispersed acicular α′ martensite, which endow it with optimal mechanical properties. Additionally, benefiting from the rapid formed passivation film, which is predominantly composed of dense and stable high-valent oxides (TiO2) on the outer layer, this alloy also exhibits the best corrosion resistance. This study indicates that TC4 alloy with excellent comprehensive properties can be achieved through SLM process regulation, making it a highly potential material for biomedical applications.