Studies on compositionally graded silicon carbide dispersed composite surface on mild steel developed by laser surface cladding

Abstract

In the present study, an attempt has been made to develop a compositionally graded SiC dispersed phase on the surface of mild steel substrate by two steps laser surface cladding technique, with a top layer having 85% Fe + 15% SiC and bottom layer of 95% Fe + 5% SiC. Laser surface cladding was conducted using a continuous wave CO₂ laser, and simultaneous feeding of a mixture of Fe and SiC (in the above mentioned ratio) with Ar as shrouding atmosphere. The microstructure of the composite layer consisted of dispersion of SiC particles in the matrix of ferrite and iron silicide (Fe₂Si). In the clad layer, SiC particles were found to be partially dissociated and the degree of dissociation was higher at the bottom layer as compared to the top layer. Area fraction of particles was found to be maximum at the surface and decreased with depth. The microhardness of the surface was improved to a maximum of 600 VHN (at the surface) as compared to 190 VHN of mild steel substrate and decreased gradually with depth. A significant improvement in wear and corrosion resistance on the clad surface was observed.