Laser Heat Treatment of Cast Irons—Optimization of Process Variables: Part I

A 1.2 kw CO₂-CW laser operating in ring and Gaussian beam modes was used to surface harden gray and ductile cast irons. The microstructure, case depth, hardness, surface integrity, and distortion were studied as functions of process variables (i.e., laser power, focusing optics, beam size, scan rate and thickness of the specimen). The results indicate that the ring mode is preferred over Gaussian whereas ductile iron response to laser heat treatment is better than gray iron. The maximum case depth achieved with minimum melting was 0.38 mm, and the maximum coverage rate obtained was 322.58 mm²/s.