Microstructures and properties of flash butt welded joints of austenitic-bainitic alloy steel railway switch and U75V rail

Heterogeneous steel joints of austenitic-bainitic steel railway switch and U75V rail were welded by flash butt welding.The microstructure, micro-hardness, impact toughness, tensile strength and fatigue properties of the joints were tested, and the effects of normalizing treatment on the hardness, strength and toughness were investigated.The results showed that the hardness distribution of the flash butt welded joints was obviously improved after normalizing treatment at 900±20℃.The impact toughness, tensile strength was also improved greatly.The grains inWM (weld metal) and HAZ(Heat affectecl zone)were refined.The welded joints possessed synthetically excellent mechanical properties.