An experimental investigation on metal surface hardening by means of diode laser treatment

Surface treatment of steel, for a higher wear resistance, is necessary in all industrial branches that deal with steel. One of the most effective methods of metal surface heat treatment is represented by laser hardening. In general, compared to other techniques, laser hardening needs a much lower heat input into the material. Compared with other conventional processes, diode laser treatment allows to obtain some advantages, such as minimum distortion in the parts and selective hardening of specific areas of components. In this paper, an experimental investigation on the surface thermal treatment of different steels by means of a diode laser was carried out. Experimental tests were performed on three types of steels, selecting different values of beam power and workpiece speed. Hardness and micro-hardness measurements were executed on the treated samples in order to assess the influence of laser machining parameters and workpiece materials on the treatment process. Experimental results were compared with those obtained by using a mono-dimensional thermal model. The morphology of heat affected zone of the specimens was investigated by scanning electron microscopy.