选用富氩低氧化性的Ar+CO2+O2三元混合焊接气体(即Rich-argon Lower-oxidizability Ar+CO2+O2三元混合气体,简称RALO三元混合气体),通过与传统(φ)(Ar)80％+(φ)(CO2)20％二元混合焊接气体(简称二元混合气体)相对比,研究机车车体Q345E钢MAG焊接头的组织和性能.试验结果表明,RALO三元混合气体的焊缝成形较为平滑、美观;三元混合气体的焊缝低温冲击韧性略高于二元混合气体,冲击吸收功Akv(-40℃)值高出约l3％;选用三元混合气体或二元混合气体进行焊接,MAG焊接头的组织特征土差别不大,即组织类型相同、形貌特征相似、晶粒尺寸相近,且焊接接头塑性良好,静载拉伸试验试样均断裂于远离焊缝的母材处.%In this paper,the microstructure and mechanical properties of welded joints of MAG welding with RALO (rich-argon loweroxidizability) Ar+CO2+O2 ternary mixed shielding gas (RALO gas) of steel Q345E are studied.The results show that comparing with traditional (φ)(Ar)80％+(φ)(CO2)20％ binary mixed shielding gas (binary gas),using RALO gas makes welds smoother and better;the low temperature impact toughness of welds of RALO gas is a little more than that of binary gas;the value of impact absorbing energy A kv (-40 ℃)of RALO gas is about 13％ higher than that of binary gas;when using these two kinds of gas for MAG welding respectively,the microstructure characteristics of welded joints have little difference,namely same type of microstructure,similar appearance characteristic and close grain size.Moreover,both the plasticity of welded joints is good and the static tensile test specimens all fracture in the base metal far away from the welds.
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