According to welding characteristics of ultra-low carbon bainitic steel HQ785DB,a submerged arc welding wire was developed on the basis of low carbon steel wire.Thus,the steel was welded with the welding wire and fluorine alkali SJ101 flux.The microstructure,mechanical properties and impact fracture morphology of weld metal were studied.The results show that the microstructure of the weld metal was mainly acicular ferrite and lath bainite mainly,and a small amount of granular bainite precipitated and dispersed in the weld metal.The tensile strength of weld metal was 806.25 MPa,the elongation was 1 6.78% and the impact toughness at 20 ℃ was 183.25 J.There were a large number of dimples in impact fracture surface,which mainly exhibited micro-void accumulation ductile fracture.%针对超低碳贝氏体钢 HQ785DB 的焊接特点,在低碳钢焊丝的基础上设计了一种埋弧焊用焊丝,将该焊丝匹配氟碱型 SJ101焊剂对该钢进行焊接,研究了焊缝金属的显微组织、力学性能及冲击断口形貌.结果表明：焊缝金属组织以针状铁素体和板条贝氏体为主,另有少量弥散分布的粒状贝氏体；焊缝金属的抗拉强度为806．25 MPa,伸长率为16．78％,20℃时的冲击吸收功为183．25 J；冲击断口上存在大量韧窝,以微孔聚集型的韧性断裂为主.
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