Laser surface treatment of grey cast iron by high power diode laser

A grey cast iron surface was heat treated by a 1 kW diode laser to improve the hardness and wear resistance of the surface. Based on a temperature measurement and control system, different levels of surface temperature and scan speed were investigated for single and multi-pass hardening processes. A homogeneous hardened zone with hardness 700–800 HV0.3 was obtained in cross section regardless to the process temperature and scan speed during single pass laser hardening. Considering the process productivity, the optimal combination of high temperature and high scan speed was used to identify the process condition to be used in the multi-pass laser hardening. The selected parameters were then applied in large surface treatment to investigate the effect of the overlapping procedure on the surface properties. Different overlapping lengths were investigated to produce a large hardened area with uniform hardening depth and hardness.