Investigation of Austenitic Stainless Steel Coatings on Mild Steel Produced by Friction Surfacing Using a Conventional CNC Machining Center

Abstract

The friction surfacing process allows deposition of similar and dissimilar coatings in the solid state, avoiding some of the problems associated with conventional coating methods in which fusion is involved. In the present work, a viability assessment of producing AISI 304 austenitic stainless steel coatings on AISI 1020 low-carbon steel substrates using a machining center with Computerized Numerical Control (CNC) instead of dedicated friction surfacing equipment was pursued. The influence of consumable rod rotation and translation speed, as well as substrate surface roughness on the geometry and adhesion of the coatings was evaluated. The microstructure of the stainless steel coatings was investigated by optical and scanning electron microscopy, while microhardness analysis was performed in order to evaluate properties near the coating-substrate interface. Finally, the electrochemical corrosion behavior of the coatings and the as-received AISI 304 steel consumables in 0.5M H 2 SO 4 solution containing naturally dissolved O 2 was compared. The results revealed that the friction surfacing process can be applied in non-specialized machinery, since the manufactured coatings exhibited good adhesion and corrosion resistance. The formation of hard bands in the coatings was identified near the interface region and the adhesion of the coatings was found to be influenced by initial substrate roughness.