Microstructure and Properties of Domex700MC HSLA Steel Joints Welded by Flux-cored Wire CO₂ Shielded Welding

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).