Improvement in wear characteristics of the AISI M2 by laser cladding and melting

The interest of high speed steel (HSS) for wood cutting tools remains very important because of their good tool edge accuracy and easy grinding. The main problem is their low resistance to both mechanical and chemical wearing. Resistance of HSS cutting tools to wearing is a primary concern in the applicability of the HSS cutting tools to a wood cutting operation. In order to increase their performance, a laser melting and cladding applied on the tool edges is presented in this paper. First, the annealed AISI M2 bar was melted, and the M2 powder was cladded onto the AISI L2 substrate by a laser beam. The microstructure and microhardness of the M2-clad and M2-melted were characterized. Second, their wear resistance was tested for cutting wood. The experimental results showed that the microstructures on the clad zone (CZ) of M2-clad and melted zone (MZ) of the M2-melted reveal fine and homogeneous iron dendritic structure, in which whole primary carbides were completely dissolved during laser cladding and melting. The energy dispersive spectroscopy (EDS) analysis indicated that the M2-clad reveals CZ microstructure with more uniform distribution of fine carbides compared to MZ microstructure. The M2-clad and M2-melted, which present almost the same microhardness, have larger microhardness compared to the M2-conventional. The results of wearing tests showed that the M2-clad and M2-melted cutting tools are better in wear resistance, edge roughness, and suffer less edge fractures than the M2-conventional peeling tool. Laser melting and cladding are considered to be valuable techniques to improve the performance of the M2 high speed steel cutting tools for wood machining application. (C) 2010 Laser Institute of America.