Laser Surface Hardening of Ductile Irons 2014-28-0021
Desired mechanical properties including wear resistance at affordable price are the key parameters for which ductile cast irons are widely selected. Particularly, in many automobile applications like brake cylinders, camshafts, connecting rods, gears, pistons and yokes ductile iron is used. Traditionally surface heat treatments like induction hardening and in recent times electron beam and laser hardening are used to improve wear and fatigue resistance of ductile irons. However, the laser surface hardening has a lot of advantages over others such as low distortion due to high power density, flexibility, accuracy, lack of quenching medium and limited grain growth.
In this work, laser surface hardening of Ferrito pearlitic ductile iron grade has been carried out. Hardening was performed with a 400W continuous wave fiber laser with the objective to investigate the effect of local tempering in continuous laser multi-pass laser surface hardening on hardness profile of the specimen. Experiments were conducted by varying four process parameters namely power density, scanning speed, scan length and beam overlap. These process parameters were optimized. Surface characterizations of laser hardened samples were made by metallography and hardness traverse.