Abstract:

As is well known, titanium alloy precipitates when subjected to aging treatment, which poses great influence on its mechanical properties. Thus, solution and solution-aging treatments were conducted in this work, and the wear performance was investigated under different normal loads. The results showed that acicular α′ martensite in the original selective laser melted Ti-6Al-4V was decomposed into α + β phases after the solution treatment, and then Ti₃Al nanoparticles clusters were further formed in the α-matrix after the solution-aging treatment. The coefficient of friction decreased straightly as the normal load was increased from 20 to 100 N, and the wear mechanisms were characterized by abrasion, adhesive and oxidative wears. The wear rate of solution and solution-aging treated samples increased significantly comparing to the as-built counterpart, but the increment of the solution-aging treated sample was smaller than that of the solution-only treated sample, because of the Ti₃Al precipitation in the solution-aging treated sample. These particles provided ball-like effect, reduced material losses and stabilized the wear process. All these factors contributed to the improvement in wear properties of the parts made by selective laser melting.

Key words: Selective laser melting, Ti-6Al-4V, Wear performance, Heat treatment