Influence of post fabrication heat treatments on the fatigue behavior of Ti-6Al-4V produced by selective laser melting

Abstract

Selective Laser Melting (SLM) is characterized by a layer-wise building process that enables the near net shape production of parts with a high geometrical complexity. The SLM process leads to the build-up of thermal stresses, while the rapid solidification leads to segregation phenomena and the development of non-equilibrium phases. To reduce thermal stresses and to optimize the microstructure and the mechanical properties for the specific application, suitable post-production heat treatments should be defined. Four different heat treatments in vacuum of SLM Ti6Al4V were investigated in relation to the fatigue behavior. Tensile and fatigue specimens were produced with a SLM system using the optimized process parameters. Microstructures before and after heat treatment were characterized by metallographic methods. Two post fabrication heat treatments are promising in terms of fatigue strength of as-built SLM Ti6Al4V. The role of surface machining was also investigated for one heat treatment condition.