Relationship between laser parameters, microstructure and corrosion behaviour of a laser surface treated AZ91D magnesium alloy

Laser surface melting (LSM) is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In this case, a high power diode laser (HPDL) was used to produce laser surface melting (LSM) treatments on the surface of the Mg alloy AZ91D. Laser-beam power range from 375-600 W and laser-scanning speed (45-60-90 mm s-1) was used to produce different treatments with different microstructures which present different corrosion behaviour. A relationship between laser parameters, microstructure and corrosion behaviour was proposed. Despite the fact that microstructural homogenization of the treated surface was produced by LSM treatments, the corrosion rates were within the scatter of the as-received AZ91D Mg alloy. However, modification of the corrosion morphology was achieved.