Material efficiency of laser metal deposited Ti6Al4V: Effect of laser power

Abstract

The economy of using Laser Metal Deposition (LMD) process in the manufacturing of aerospace parts depends on the right processing parameters. LMD is an additive manufacturing technology capable of producing complex parts directly from the CAD model data in one single step. LMD is also capable of repairing high value component parts; it is a promising technology for producing aerospace part that will reduce component weight as well as reducing the buy-to-fly ratio. Ti6Al4V is an important aerospace alloy and a very expensive material. This study investigates the influence of laser power on the overall economy of laser metal deposited Ti6Al4V. This was achieved by depositing Ti6Al4V powder on Ti6Al4V substrate at a varying laser power of between 0.4 and 3.0 kW while maintaining the scanning speed, the powder flow rate and gas flow rate at constant values of 0.005 m/s, 1.44 g/min and 4 l/min respectively. The substrate was sand blasted, cleaned with acetone and weighted before the deposition started. After the deposition process, the substrate containing the deposit was cleaned with wire brush and acetone to remove the unmelted powder particles on the surface of the deposit and the substrate, and then reweighed to know the mass of powder that was really deposited. Also, the width and height of the deposit were measured using the vernier caliper and the material efficiency was determined using the set of equations developed. The soundness of the deposits was studied using the optical microscope for the cross section of the samples prepared metallurgically and etched with Kroll’s reagent. The study revealed that as the laser power is increased, the powder efficiency is also increased. The deposit width also increases as the laser power is increased. The deposit height on the other hand initially increases as the laser power is increased and started to decrease as the laser power is further increased. The results are presented and fully discussed.