Laser beam welding hard metals to steel

Laser beam weldability of hard metals to steel was examined with high power (cw) CO2 laser, (cw) Nd:YAG laser and (pw) Nd:YAG laser. Steel/hard metal joints, with 2.5 mm thickness, welded by the three laser systems, for comparison, will be presented. Two different hard metals compositions (K10 and K40) were examined. Power (P), speed (s) and vertical focal point position (f.p.p.) were investigated. To reduce the problem of porosity and crack formation in the hard metal, the parameter, tw, horizontal distance from the beam to the joint was also investigated. Weld bead size, microstructure, bending tests and hardness were evaluated.