Development of a laser surface melting process for improvement of the wear resistance of gray cast iron

A new laser heat treatment, involving the heating of the metal surface above its melting point, was developed on gray cast iron. Microstructural analysis performed by transmission electron microscopy of remelted layers showed several types of structures depending on the cooling rate of the workpiece.Laboratory wear tests were carried out on a pin-on-ring machine simulating the cam-and-tappet system to evaluate the tribological properties of the laser-remelted layers. Results were similar to those obtained in an induction-hardened nodular cast iron conventionally used for automotive applications.Melted layers 0.5–0.7 mm thick with a hardness above 50 HRC were obtained on an automotive camshaft.