Microstructural and Corrosion Resistance Studies on SUS 420F and EN32B Steels Under Surface Treatment by High Power Diode Laser

This research work deals with studies on the laser surface melting (LSM) of SUS 420F plastic mould steel and EN32B plain low carbon steel by a high power diode laser (HPDL). The laser treated samples were investigated by scanning electron microscopy (SEM) for microstructure and corrosion resistance was carried out using electrochemical method. In plastic mould steel, the microstructure is columnar dendrite and fine martensite microstructures with residual austenite phases are formed. The microstructures were transformed from columnar dendrite to randomly oriented ones, as the laser power was increased from 2 to 3 kW. On the other hand, the low carbon steel laser surface melted by the HPDL has created lath martensite microstructure. The potentiodynamic electrochemical corrosion method reveals improved corrosion resistance in the laser treated layers.