Fatigue strength improvement of selective laser melted Ti6Al4V using ultrasonic surface mechanical attrition

ABSTRACT Ultrasonic surface mechanical attrition treatment (SMAT) was employed to modify the surface microstructural layer of SLM Ti6Al4V ELI biomedical material to improve the fatigue performance. The SMAT method can introduce a nanostructured layer in the SLM sample surface by imposing high-strain-rate plastic deformation. The nanostructured layer improves the mechanical strength of the SMAT-affected zone and induces compressive residual stress parallel with the surface which suppress the initiation of cracks. As a result, the specimen after SMAT exhibits significantly higher fatigue strength than the non-treated sample in both low- and high-cycling regime. GRAPHICAL ABSTRACT IMPACT STATEMENT This research demonstrates that surface mechanical attrition treatment (SMAT) is a promising post-processing technology for selective laser melting. SMAT improves the fatigue strength of selective laser melted Ti6Al4V by 100%