Microstructural Evolution and Bio-corrosion Characteristics of Cold-Rolled Ti-6Al-4V Alloy Fabricated Through Selective Laser Melting for Implant Applications

Abstract

The microstructural evolution, mechanical properties, and bio-corrosion behavior of Ti-6Al-4V alloys processed by cold rolling and annealing were investigated to address the need for improved biomedical implants. This study aimed to determine and compare these properties in cold-rolled and annealed cold-rolled SLM-fabricated Ti-6Al-4V specimens. The specimens AMCR01 and AMCR02 revealed elongated grains due to cold rolling and phase compositions of 73% α-Ti and 27% β-Ti in AMCR01, and 87% α-Ti and 13% β-Ti in AMCR02, with inhomogeneous β-Ti clustering. Microhardness tests showed increased hardness in cold-rolled specimens, while tensile tests indicated enhanced strength compared to annealed specimens, which exhibited reduced strength due to grain enlargement. Fractography revealed combined ductile and brittle fracture modes in both conditions. Immersion corrosion tests in SBF solution demonstrated enhanced corrosion resistance with an increased rolling reduction ratio, with annealed specimens showing the lowest corrosion rate. The surface morphology supported these findings, indicating the augmenting effect of cold rolling and annealing on corrosion resistance.