INVESTIGATION OF METALLURGICAL AND MICROHARDNESS PROPERTIES OF TITANIUM ALLOY   IN LASER METAL DEPOSITION PROCESS

R. M. Mahamood; Abdulkareem S. , Aweda J.O.; K R Ajao

R. M. Mahamood Department of Mechanical Engineering, University of Ilorin, Nigeria.
Abdulkareem S. , Aweda J.O. Department of Mechanical Engineering, University of Ilorin, Nigeria.
K R Ajao Department of Materials and Metallurgical Engineering, University of Ilorin, Nigeria

Keywords: Metal Deposition Process, Laser power, Macroscopic Banding, Microhardness, Microstructure

Abstract

This paper reports on the investigation of metallurgical and microhardness properties of laser metal deposition of Titanium alloy- Ti-6Al-4V. Ti-6Al-4V substrate and Ti-6Al-4V powder (150-200 m) both at 99.6% purity were used in this study. The input laser power varied between 0.8 and 4.0 kW while other processing parameters were kept constant. They include the scanning speed of 0.005 m/sec, powder flow of 1.44 g/min and the gas flow rate of 4 l /min. The microstructure and the microhardness were examined under the optical and scanning electron microscope. The microhardness was measured using the Vickers hardness tester. The study revealed that the layer band occurred in all the samples except those samples at very high laser powers. The microstructure of the heat affected zone is characterized with fine globular primary alpha and beta grains at low laser power and become coarse as the laser power was increased. The microhardness was found to initially increase and then decrease as the laser power was increased beyond 3 kW.