Microstructure and Mechanical Properties of Laser Metal Deposited Ti-6Al-4V

Laser metal deposition (LMD) is a near net shape manufacturing process in which the final shape of a part or component is built layer-by-layer. The energy of a laser beam is used to melt a wire of the selected pre-alloyed material onto a substrate or work piece. In the present study, the mechanical properties of laser metal deposited Ti-6Al-4V have been evaluated with respect to the yield strength, ultimate tensile strength, ductility and low cycle fatigue at room temperature and at 200 degrees C. In addition, fractographic and metallographic studies were carried out in order to correlate the mechanical behaviour with grain morphology and microstructure. The yield strength, ultimate tensile strength, ductility and the low cycle fatigue properties of LMD material were all better than or equal to the corresponding mechanical properties of standard cast Ti-6Al-4V material. It was also found that defects, such as pores and surface irregularities, significantly reduce the fatigue life of LMD Ti-6Al-4V material, leading to premature fracture when present.