Study on Weldability of the Grain Boundary Allotriomorphic Ferrite/Granular Bainite (F_(GBA)/Bg) Duplex Steel

摘要

The weldability of F_(GBA)/Bg duplex steel, newly developed at Tsinghua University, has been evaluated by slit type cracking test and the maximum hardness. The microstructure and mechanical properties of weld joint and heat affected zone (HAZ) have also been investigated. The results show that F_(GBA)/Bg duplex steel has low cold cracking sensitivity and superior weldability, and can be welded by high heat input welding. The HAZ microstructure of F_(GBA)/Bg duplex steel is mostly composed of low carbon martensite, which has low cold crack susceptibility and better strength-toughness combination. F_(GBA)/Bg duplex steel plate (JB800) is easily welded with welding electrode E7515 at lower preheating temperature or no preheat before formal welding, and it meets the relevant mechanical property requirements well.