Influence of Modified Microstructures and Characterized Defects on Tensile Properties and Anisotropy of Selective Laser Melting-Produced Ti6Al4V Alloys

The influences of selective laser melting (SLM) processing and post-processing on microstructure, crystallographic texture and defect characteristic, as well as the tensile property and anisotropy of SLM-produced Ti6Al4V alloys, were extensively studied. The results showed that the microstructure and the defects including micropore, keyhole and lack of fusion (LOF) can be controlled through the optimization of SLM processing and post-processing procedures. Mechanical tests demonstrated that the tensile properties were dependent mostly on the features of alpha phase/colony which could result in two types of fracture modes. The laminar heat-affected zone (HAZ) and LOF caused by SLM processing should be responsible for the anisotropy in strength and ductility, respectively. However, the presence of columnar grain structure, inherited weak texture, micropore and keyhole has limited effect on the tensile behaviors. The anisotropy can be alleviated through coarsening alpha phase, forming alpha colony and controlling defects such as the laminar HAZ and LOF with various process parameters and heat treatment procedures.

Automated summary

The influences of selective laser melting (SLM) processing and post-processing on microstructure, crystallographic texture, and defect characteristics of SLM-produced Ti6Al4V alloys were extensively studied. The results showed that the microstructure and defects can be controlled through optimization of the SLM process and post-processing. Mechanical tests demonstrated that tensile properties were mainly dependent on the features of alpha phase/colony, leading to two types of fracture modes. The anisotropy in strength and ductility was attributed to the laminar heat-affected zone (HAZ) and lack of fusion (LOF) caused by SLM processing, respectively.