Effect of high power diode laser surface melting on wear resistance of magnesium alloys

In the present work, an attempt has been made to improve the surface hardness and wear properties of magnesium alloys AZ31 and AZ61 through solid solution hardening and refinement of microstructures using a 1.5 kW high power diode laser (HPDL) as a heat generating source. One millimetre thick uniform overlapping melt tracks were produced on Mg alloy samples. Laser-melted samples were subjected to a two-body abrasive wear test using a modified pin-on-disc set up. The hardness and wear resistance of laser-melted samples were found far better than the as-received Mg alloy substrates. Scanning electron microscopy was used to examine microstructure of the laser-melted layers and the worn surface morphology. Fine microstructures were observed with an average grain size of less than 5 μm.