Fatigue properties of Ti6Al4V prepared by selective laser melting

Abstract

The microstructure and fatigue properties of specimens prepared using the selective laser melting technology were analyzed and compared to specimens produced of Ti6Al4V alloy by a conventional way, it means by the casting and forging. The forged samples were studied in both as-received and annealed + hot isostatic pressed conditions; the selective laser melted samples were tested after annealing + hot isostatic pressing. It was proved that the forged specimens showed better fatigue properties than the selective laser melted samples, according to defects formed during the powder-bed-based additive manufacturing process. Small differences in fatigue life were observed for both heat treatment conditions of the forged samples. Despite certain porosity, the selective laser melted samples showed high endurance limit at stress level of 320 MPa. Nevertheless, the limit strength value was lower by 26% and 36% comparing forged specimens in as-received and heat treated + hot isostatic pressed conditions, respectively. The microstructure of all tested samples was formed of α+β phases depending on heat treatment condition. The differences in fatigue fracture features of the forged or selective laser melted specimens corresponded to the microstructure, defects and porosity presence.