Rolling contact fatigue performance evaluation of Ti–6Al–4V parts processed by selective laser melting

Selective laser melting (SLM) of titanium components is gradually gaining popularity in various fields, such as aerospace, automobile, and medical for the purpose of saving material and reducing the carbon footprint. To capitalize on their benefits, the mechanical properties of parts fabricated by SLM must meet engineering requirements. Fatigue properties are particularly important for the performance of safety-critical structures. In this research, rolling contact fatigue (RCF) tests were performed for SLM fabricated Ti–6Al–4V samples in differently post-treated conditions to investigate the effect of different post-processing methods on the fatigue properties and, as a comparison, forgings of Ti–6Al–4V were also tested. It was found that the RCF properties of the Ti–6Al–4V generated by SLM were superior to those of the forged specimens and strengthened after polishing and heat treatment. The worn surfaces were observed by using an optical microscope, and the results indicated that surface and subsurface defects are the main causes of fatigue crack initiation and the residual stresses enhance fatigue crack growth.