Domex700MC低合金高强钢药芯焊丝CO2气体保护焊焊接接头的组织与性能

Microstructure and Properties of Domex700MC HSLA Steel Joints Welded by Flux-cored Wire CO_2 Shielded Welding

用药芯焊丝CO2气体保护焊焊接Domex700MC低合金高强钢,用光学显微镜、硬度计和冲击试验机等对焊接接头的显微组织和力学性能进行了分析。结果表明:焊缝金属晶粒细小且分布均匀,有较多针状铁素体,但熔合区组织比较粗大,使熔合区附近塑性降低,为焊接接头的薄弱部位;焊缝金属显微硬度较高,为315 HV,而在热影响区为225 HV,出现软化现象;焊接接头力学性能优良,具有较高的抗拉强度(630.94 MPa)和冲击功(135.34 J)。

The Domex700MC high strength low alloy（HSLA） steel was welded by the CO2 shielded welding process with flux-cored wire. The microstructure and mechanical properties of the welded joints were analyzed by optical microscope, hardness testor and impact testing machine. The results show that the microstructure distribution of the weld metal was uniform and contained mass of acicular ferrite, but the plastic property was reduced in the heat affected zone（HAZ） because of grain growth. The micro-hardness of weld metal（315 HV） was higher than that of the other area, e. g, the micro-hardness of the HAZ was 225 HV and thus softening existed in this area. The mechanical properties of the welded joints were good, with relatively high tensile strength（630. 94 MPa） and impact power（135. 34 J）.