Study On The Microstructure And Properties Of The Welded Joint With Weathering Weld Material For Uncoating Weathering Bridge Steel

With the development of the bridge industry,weathering steels used for bridge construction with high corrosion resistant and strength is improved gradually.It is very important to carry out the studies of welding materials and related welding technology to obtain welded construction with high corrosion resistant,toughness and strength.Therefore,the development of the welding materials with high strength and corrosion resistant have important theoretical and practical significant.In this study,weather-resistant gas metal arc welding wire and submerged ard welding wire with high corrosion resistant,toughness and strength are successfully developed.In this paper,the influence of different heat input,shielding gas type and welding flux on weld metal of microstructure and properties were studyed.The study results indicate that the microstructure of the columnar zone is mianly composed of acicular ferrite(AF),grain boundary ferrite(GBF)and ferrite-side-plate(FSP).The microstructure of the weld heat-affected zone is mainly composed of quasi-polygonal ferrite(QPF).The amount and size of M-A constitutes are increased varying with heat imput by argon-rich gas shielded welding,and the impact toughness of weld metal is decreased gradually.The amount and size of M-A constitutes are decreased firstly and then increased varying with heat imput by submerged arc welding,and the impact toughness of weld metal is decreased firstly and then increased.The amount of acicular ferrite is low by CO2 gas shielded welding compare to submerged arc welding.The impact toughness of weld metal is low.The impact toughness of weld metal is high when XF-BG and JQSJ101 NQ flux were used.The accelerated corrosion tests indicate that the weatherability of weathering steel and its joint are higher than ordinary steel's.the weatherability of weathering steel joint is equivalent with weathering steel by using weathering resistant wire.The joint of weathering steel can not be weak link in weathering steel corrosion.