Metal-ceramic joining by laser

Within the scope of increase in cutting tools efficiency, a CW CO2 laser beam has been used for butt welding sintered tips containing cobalt and tungsten carbide to a medium carbon steel core. After optimization of the laser processing conditions, full penetrating, sound and homogeneous welds are observed. Hardness is found to be nearly constant across the entire weld bead cross-section. Micrographic observations in the same area show a fine dendritic microstructure ; microanalysis (EDS) as well as X-ray diffraction experiments reveal that dendrites contain mainly iron and cobalt, while tungsten has segregated in the interdendritic zone where complex (Fe - Co - W) rich carbides are likely to form.