Effect of post-treatment on the microstructure and mechanical properties of selective laser melted Ti6Al4V lattice structures

Abstract

Purpose The purpose of this paper is to investigate the post-treatment processes on lattice structures of selective laser melting. Moreover, the effect of pressure during hot isostatic pressing (HIP) is determined. Design/methodology/approach Three post-treatment processes, annealing at 650°C, 920°C and HIP were adopted. The microstructure evolution and mechanical properties of selective lasering melted Ti6Al4V lattice structures after post-treatment were systematically investigated by optical microscope, scanning electron microscope, electron backscattered diffraction, differential scanning calorimetry and quasi-static mechanics tests. Findings The main findings in this paper are as below: first, the pores existing in the samples as-fabricated, annealed at 650°C and 920°C are disappeared after HIP. Second, the microstructure and compressive properties after HIP are similar to that after pure annealing at the same temperature. However, the HIPed sample had the highest number of cycles to failure. Third, the fracture mechanism of as-fabricated samples changes from mixed fracture to the micro-voids accumulation fracture after post-treatment processes. Originality/value HIP post-treatment can be replaced by annealing at the same temperature when the requirement for porosity and fatigue life is not very high.

Effect of Microstructural and Textural Anisotropy on the Tensile Properties of Selective Laser Melted and Annealed Ti6Al4VE Alloy

“…[ 31 ] The β phase with the body‐centered cubic (BCC) crystal structure has better plasticity in contrast to the α ′ phase. [ 32 ] The 900 °C annealed alloy, especially the 900‐XZ, has the best plastic deformation capacity due to the increase of α / β phases and decomposition of α ′ phases in the optimum state. However, the coarse lamellar α microstructure in the 1050 °C annealed alloys damages the deformation ability of the alloy and causes a decrease in plasticity.…”