Microstructure, Mechanical Properties, and Wear Behavior of Dissimilar Metallic Coatings for Steel Discs of Butterfly Valves

In the present work, coating materials that can be welded to the EN 1.6220 low-alloy steel disc of a butterfly valve and are also compatible with the seal material, i.e., 17–4 PH steel, are studied. 312 duplex stainless steel, 316 austenitic stainless steel, and Stellite 6 are identified as potential coating materials for the disc based on Cobweb analysis and are welded to the disc using metal active gas (MAG) welding (312 and 316 steel coatings) and powder plasma arc welding (Stellite 6 coating). Microstructural analyses and Vickers hardness measurements of the weld joints are performed. The surface roughness and wear behavior of the coatings are also studied. Nanoscale wear phenomena and consequent phase transformations are studied using molecular dynamics simulations. The results show that 312 and 316 stainless steels are suitable coating materials for the disc.