Microstructure, texture and mechanical properties with raw surface states of Ti-6Al-4V parts built by L-PBF

Abstract

Due to dramatic thermal gradients and cooling rates induced by Laser Powder Bed Fusion (L-PBF), Ti-6Al-4V as-built parts show a fine martensitic microstructure with high residual stresses that are detrimental for their mechanical behaviour. In order to optimize the properties and meet the product requirements, post-processing heat treatments are often compulsory. The present work first describes the microstructure (residual stresses, beta grains and laths size, crystallographic texture) and the mechanical behaviour (impact and tensile tests) of as-built parts with raw surface. Then, one discusses the effect of a stress-relieve sub-transus heat treatment on the strength/ductility compromise.