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

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 us 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 has been carried out. Experimental tests have been performed on three types of steels, selecting different values of beam power and workpiece speed. Hardness and micro-hardness measurements have been executed on the treated samples in order to assess the influence of laser machining parameters and of workpiece materials on the treatment process. Experimental results have been compared with those obtained by using a mono-dimensional thermal model. The morphology of the heat affected zone of the specimens has been investigated by scanning electron microscopy