Functionally graded material: Carbon gradient on IF steel

The following research activity focuses on the creation of carbon gradient inside interstitial free steel (IF steel) in order to increase its strength using temperatures that are lower than the one used in carburizing treatments. Tensile coupons of IF steel are previously coated on both sides with an amorphous carbon containing layer using physical vapor deposition (PVD). Tensile samples have been annealed at different temperatures. It is shown that an increase of the yield strength as well as the appearance of a Liiders' plateau is associated with carbon diffusion at temperatures higher than 430°C. The effect of film thickness on carbon diffusion and resulting mechanical properties was also investigated. The fracture surface of the samples was observed under a scanning electron microscope to extract the sample ductility. Copyright © 2013 MS&T'13®.