Friction stir welding of high carbon steel with excellent toughness and ductility

 The difficult of welding of high carbon steels is due to a greater tendency of martensite formation in the joint, resulting in typical welding problems such as a decrease in toughness. The present study examines the friction stir welding of hyper-eutectoid steel (0.85 mass% C, AISI-1080) under a maximum temperature below A1 (726 °C) in order to exclude martensite transformation during the joining process. Joining without the formation of martensite structure can be successfully achieved and the joint exhibits good toughness.