Heat treatment of additively manufactured Ti-6Al-4V alloy: Microstructure and electrochemical properties

Abstract

The effects of heat treatment on the microstructure of additively manufactured (AM) Ti-6Al-4V were investigated. The relationship between the microstructure characteristics and the surface activity of AM Ti-6Al-4V was explored. Electrochemical analysis results revealed that AM Ti-6Al-4V annealed at 940 °C exhibited a stronger ability to corrosion resistance, followed by an alloy cooled at 1020 °C. The Ti-6Al-4V alloy with aging treatment at 540 °C showed a higher corrosion rate. The difference in the corrosion rate of the specimens was obtained through corrosion experiment conducted using a 0.5 mol L–1 hydrochloric acid-hydrofluoric acid solution, and the results of the initial stage of immersion were consistent with the electrochemical measurements. Variations in the phase content and texture were the main factors affecting the corrosion resistance of Ti-6Al-4V. An increase in the β phase and a decrease in the α’ grains were beneficial to improving the corrosion resistance performance. Specimens with a higher< 110 >texture strength possessed preferable corrosion resistance under more than 2 days of immersion. The preferential growth of the oxide film in the direction of< 110 >//ND was considered a critical factor in improving the corrosion resistance of AM Ti-6Al-4V alloy.