STUDY AND ANALYSIS OF WEAR AND MICRO STRUCTURAL CHANGES ON CAST IRON UNDER LASER TREATMENT

In this thesis Fiber laser techniques are used for the surface engineering of engine cylinder liner. Laser hardening produces wear resistant tracks by microstructural transformations. In this work application of the laser hardening process on gray cast iron cylinder liner, a material that is widely used in automotive engine, is investigated based on the observations of microstructure transformations in the influence of the process parameter. An important conclusion is that the surface quality of gray cast iron can be enhanced by Power density controlled laser surface hardening. The average microhardness of cylinder liner laser treated tracks increased from 250 to 400-700 HV in the transformed zone that consisted mainly of martensite, retained austenite and remaining cementite lamellae and undisclosed graphite flakes. Finally, the wear behavior of laser hardened cylinder liner is tested by dry sliding in a varying load condition.