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 A(1) (726 degrees 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. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.