EFFECT OF THE SURFACE MORPHOLOGY AND SURFACE FINISH ON THE CORROSION RESISTANCE OF HEAT TREATED Ti6Al4V VIA DIRECT METAL LASER SINTERING

Direct Metal Laser Sintering is an additive manufacturing process that is used in fabricating titanium alloys. Due to high localized thermal input and fast cooling rate, the as-sintered parts contain non-equilibrium phases. In Ti-6Al-4V, the as-fabricated microstructure is composed of acicular martensite with poor ductility. For biomedical implants, the major failure mode for Ti-6Al-4V is by fretting corrosion at the metallic interface in body fluid. So, proper post-treatments are required to ensure better performance. In this work, a variety of solutions, stress relieving and annealing heat treatments were conducted on Ti-6Al-4V fabricated by direct metal laser sintering. The effect of surface morphology on the corrosion behavior were experimentally investigated. The microstructure, phase percentage and lattice parameters were measured by scanning electron microscope and X-ray diffraction with Rietveld refinement. The corrosion behavior of post heat treated samples were characterized electrochemically in simulated body fluid and the effect of different surface finish were emphasized.