Surface roughness and fatigue properties of selective laser melted Ti-6Al-4V alloy

Surface roughness of selective laser melted Ti-6Al-4V alloy in as-built status is unsatisfactory for cyclic loading applications because surface defects can lead to a premature fatigue crack initiation. In this study, a trade-off between surface quality and production rate is considered in the design of laser processing parameters. It was found that higher production of selective laser melting (SLM) process inevitably leads to a higher surface roughness. With as-fabricated surface condition, samples made with laser parameters of higher production rates showed a poorer fatigue performance. The comparison of fatigue properties between machined samples and net-shape samples shows that surface roughness is a controlling factor of fatigue performance in SLM products.