EFFECT OF SCANNING SPEED TREATMENT ON THE MICROSTRUCTURE, MICROHARDNESS, WEAR AND CORROSION BEHAVIOUR OF LASER METAL DEPOSITED Ti-6Al-4V/TiC COMPOSITE

摘要

The influence of scanning speed on the microstructure, microhardness, wear and corrosion resistance behaviour of titanium alloy composite (Ti-6Al-4V/TiC composite) produced using laser metal deposition process was investigated. Rofin Sinar Nd-YAG laser was used to produce the samples at a laser power of 2.5 kW, powder flow rate of 2 g/min, and gas flow rate of 2 1/min. The scanning speed was varied between 0.005 and 0.050 m/s. The micro-structural studies were carried out using optical microscope and scanning electron microscope. The microhardness profiling was done using Vickers microhardness tester at a load of 500 g and a dwell time of 15 s. The dry sliding wear of the composite was investigated using a ball-on-disk tribometer at a load range of 25 N. The corrosion behaviour was evaluated in 3.5% NaCl solution using potentiodynamic polarization measurement method. Unmelted carbide particles, as well as dendritic TiC were used. The percentage composition and distribution of all these particles were found to change as the scanning speed was varying varied. The microhardness was found to increase with increaseding in scanning speed . The wear volume produced was found to decrease as the scanning speed was increased. The electrochemical behaviour of the composites showed that, as the scanning speed was increased, the corrosion potential and corrosion rate was found to be reduced.