Seizure-resistance cast-iron surface textured by laser decomposition of graphite phase and hardened by laser quenching

Surface texture is known to cause lubricant-pocket and debris-trap effects. It improves the tribological performance through a low friction coefficient, wear-resistant, and seizure-resistant properties. This study proposes and demonstrates a method to simultaneously texturize and harden a cast-iron surface via laser irradiation, which is called "graphite disappearance laser dimpling (GDLD)." The crevasse-like dimples are obtained by decomposing the graphite grains through laser heating and oxygen blowing. A quenched surface is also obtained by laser heating and heat-conduction cooling. The dimple area ratio (DAR) is 2-20%, which is achieved by varying the carbon content, and the graphite phases are successfully decomposed via laser irradiation and 20% oxygen blow. The surface is simultaneously hardened to 600-700 HV. The optimal DAR for seizure resistance is approximately 15%; the pressure at seizure is increased by 3 times and 1.5 times as compared with the lowest-pressure sample (DAR 1.8%) and crosshatch sample as a reference, respectively. (C) 2020 CIRP. Published by Elsevier Ltd. All rights reserved.