Research Of The Technology Property And Mechanical Property Of A New Type Agglomerated Flux For FCB-SAW

The heat input of FCB-SAW (Flux Cooper Backing Submerged Arc Welding) is larger than 100kJ with 60～90cm/min welding speed. The welding technological property of common agglomerative flux in the FCB-SAW is bad with the condition of high welding speed and large heat input. And the mechanical property even the impact toughness of E grade steel cann't been assured. Therefore, a new type of agglomerated flux with slag system of MgO-CaO-CaF₂-Al₂O₃-SiO₂ for FCB-SAW of E36 steel has been successfully developed.The regularity of every ingredient's influence on the technical property in the new tape agglomerated flux has been presented. Under the condition of 65cm/min welding speed and 110J/cm heat input of the FCB-SAW, using the welding wire H10Mn2, H08A and the back flux DQ·FCB-1R, the excellent welding technology property was obtained. The result indicated that it has stable welding arc, the favorable welding formation with beautiful with finely waviness and homogeneous width and the easily doffing. The weld was in good fusion to the base metal.The regularity of alloy element's influence on mechanical properties of welded joint in the new tape agglomerated flux has been presented. The alloy system of the new tape agglomerated flux is Ni-Mo-Ti. The alloy element can effectively reduce the content of pro-eutectoid ferrite and promote the forming of the acicular ferrite in weld metal. As result the toughness of weld joint is great promoted. The microscopic structure of the weld is mainly consisted of ferrite, pro-eutectoid ferriteand pearlier. The impact toughness value at -20℃of welding joint reach 66J, bigger than 34J, the yield strength is 455MPa, the tensile strength is 570MPa, the coefficient of elongation is 26%, the mechanical property of weld joint can satisfy the 3Y requirement of classification society of china as well as the using requirements of shipyard.