The Effect of Mixed Slurry of Fe and Graphite on the Characteristics of Laser Carburized Surface

Laser surface carburizing can be achieved by a laser alloying mechanism, which includes melting the graphite coated substrate and dissolution of the graphite in the liquid state.The drawback of laser carburizing is that process-induced cracks frequently form on the carburized surface as a result of carbon enrichment and the rapid re-solidification rates.Hence, in this study laser surface carburizing of a substrate coated with a mixed slurry of graphite and Fe powders was implemented to increase the surface hardness without surface cracking.The cracking susceptibility, carburized depth and the hardness of the carburized layer were investigated for various laser processing conditions.The results showed that a lower relative content of graphite powder in mixed slurry reduces the cracking susceptibility on the carburized surface without significantly decreasing hardness.From the analysis results, operational guides for laser surface carburizing processing are provided for achieving a crack-free carburized surface with desired hardness.