Effect of Laser Shock Peening on Properties of Heat-Treated Ti–6Al–4V Manufactured by Laser Powder Bed Fusion

Abstract

Ti–6Al–4V components fabricated by laser powder bed fusion (LPBF) suffer from high brittleness and poor toughness issues, which are largely attributed to the $${\alpha }^{^{\prime}}$$ -martensite phase of LPBF products. Post-heat treatment is often carried out to improve the toughness of LPBF products, which, however, has been reported to result in a decrease in strength, abrasion resistance, and corrosion resistance. In this study, laser shock peening (LSP) is applied to post-heat-treated Ti–6Al–4V LPBF products as a solution to achieve enhanced surface properties as well as improved toughness. By post-heat treatment only the impact toughness of the LPBF-fabricated Ti–6Al–4V could be increased by 150%, that too at a significant degradation of surface hardness, wear, and corrosion resistance. When LSP is applied to the post-heat-treated Ti–6Al–4V, impact toughness remains nearly the same, whereas surface hardness and wear resistance are recovered to approximately 92% and almost full values prior to heat treatment, respectively. LSP also decreased the corrosion rate by 64% from that of the heat-treated sample. The results showed that LSP combined with post-heat treatment is a plausible approach to achieve both high impact toughness and enhanced surface properties in LPBF-fabricated Ti–6Al–4V products.