Study On Low Spatter Welding Wire And Welding Process Of Weather Resistant Steel

As one of the important components of rail vehicle,the welding quality of high speed bogie directly affects train performance.When the existing welding materials and welding technology are used in MAG welding of SMA490BW weather-resistant steel,there are such problems as high welding spatter,poor arc stability,poor forming of weld surface,etc.In this paper,the welding spatter rate of commercial CHW-55CNH weather resistant steel welding wire matching with different protective gas was compared.Two groups of shielding gases with low spatter and good formation were selected for welding.The microstructures and properties of deposited metals using two groups of shielding gas were analyzed.A new type of ultra-low carbon weather resistant steel welding wire had been developed.The spatter rate of self-made wire and CHW-55CNH wire was compared and the microstructures and properties of the two kinds of welding wires were investigated.Five kinds of protective gases matching with commercial CHW-55CNH weather-resistant steel welding wire were selected for welding.It was found that Ar+5%CO₂+2%O₂ had the best effect on reducing spatter,which was 22.3%lower than that of Ar+20%CO₂shielding gas.The microstructures of the deposited metals with Ar+5%CO₂+2%O₂and Ar+5%CO₂shielding gas were mainly acicular ferrite and uniform.The tensile strength of deposited metal with Ar+5%CO₂+2%O₂ shielding gas reached 498 MPa and the impact absorption energy at room temperature reached 154 J.The strength of deposited metal was only 7.4%lower than that of Ar+5%CO₂shielding gas.The ultra-low carbon weather-resistant steel welding wire with high content of Cr and Ni was developed.The spatter rate of ultra-low carbon welding wire was 72.3%lower than that of CHW-55CNH wire with Ar+20%CO₂shielding gas.The deposited metal had good strength and toughness.The spatter rate of ultra-low carbon welding wire was 78.8%lower than that of CHW-55CNH welding wire with Ar+5%CO₂ shielding gas.The number of acicular ferrite in deposited metal using ultra-low carbon welding wire was increased obviously.The grain size of deposited metal was smaller and more uniform.The tensile strength of deposited metal with ultra-low carbon wire was 640 MPa and the impact absorption energy was 195 J at-40?.The strength and toughness of the two welding wire deposited metals were equal at room temperature,but the low-temperature toughness of ultra-low carbon welding wire was 31%higher than that of CHW-55CNH wire.SMA490BW weather resistant steel was welded using two groups welding process of CHW-55CNH welding wire matching with Ar+5%CO₂+2%O₂ protective gas and ultra low carbon welding wire matching with Ar+5%CO₂ shielded gas.The results showed that the low spatter welding was realized in both groups of experiments and the strength of welded joint met the requirements for high-strength matching with base metal.The welding spatter rate of ultra-low carbon welding wire was lower.