FEASIBILITY STUDY ON DIFFUSION WELDING OF MARINE GRADE GREY LAMELLAR GRAPHITE(GG) CAST IRON TO MARINE GRADE STEEL

Abstract

Grey cast iron has interconnected nature of the graphite flakes which forms a composite that imparts excellent damping capacity and make it ideal for application such as machine based and supports, cylinder blocks and brake components. However in general cast iron which carries a good proportion of carbon, sulphur and phosphorous, is poorly weldable by fusion welding because it tends to crack in the near-weld zone both during and after welding. The weldability by fusion welding may be lessened by the formation of hard and brittle microstructures in the heat affected zone (HAZ), consisting of iron carbides and martensite. Diffusion welding can be used to overcome the microstructural problems related to fusion welding. Diffusion welding is a joining process between materials wherein the principal mechanism for joint formation is solid state diffusion.