Evaluation of hatch distance and powder feed rate effects in TI-6AL-4V alloy developed by LMD technique

Abstract

Laser metal deposition provides various benefits over traditional manufacturing, and has since become the research hotspot, as demand for advanced manufacturing persists. The effects of process parameter variation on structural integrity and dimensional accuracy of Ti-6Al-4V alloy fabricated through laser metal deposition was investigated. The laser power, scan speed and gas feed rate were kept constant while overlap distance was varied between 0,3375 and 1,0125mm, and the powder feed rate was varied between 1,6 and 3,8g/min. The density of samples was studied by Archimedes method using ethanol as a wetting liquid, and dimensions were evaluated using a digital Vernier calliper. The microstructure and morphology were examined by an optical microscope (OM). The microhardness and densification of specimen were evaluated using Vickers microhardness tester and Archimedes method, respectively. The results revealed an increase in density with an increase in overlap spacing, and the opposite effect was observed for increasing powder flowrate, whereby an increase in powder flowrate was found to decrease density. The evolution of large pores was favoured by higher powder feed rate at constant overlap spaces. In addition, the microhardness of all samples was found to exceed the conventionally fabricated Ti-6Al-4V alloy.