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针对海上钻井平台桩腿用厚板低合金高强钢Q690E,采用高效机器人双丝MAG焊接系统,研究了不同CO2含量的保护气体对焊缝区力学性能及微观组织的影响。结果表明:保护气体为96%Ar+4%CO2时,焊缝金属组织以贝氏体和马氏体为主,当保护气体中CO2含量为10%和20%时,焊缝区显微组织中针状铁素体含量增多;当CO2含量为10%时,焊缝区抗拉强度最大,当CO2含量为20%时抗拉强度最小;随着保护气体中CO2含量的增加,焊缝区-40℃低温冲击韧性逐渐增大,当CO2含量从4%增大到10%时,低温韧性增大的幅度较大,随着CO2含量进一步增大,低温韧性增大幅度趋于平缓。
Aiming at the low alloy and high strength steel Q690E with thick plate and low alloyed high strength steel for the leg of offshore drilling platform, the effect of protective gas with different CO2 content on the mechanical properties and microstructure of the weld zone was studied by using high efficiency robotic double wire MAG welding system. The results show that when the shielding gas is 96% Ar + 4% CO2, the microstructure of the weld is mainly bainite and martensite. When the content of CO2 in the shielding gas is 10% and 20%, the weld microstructure Acicular ferrite content increased; when the CO2 content of 10%, the weld zone tensile strength is the largest, when the CO2 content of 20%, the tensile strength is the smallest; with the increase of CO2 content in the protective gas, the weld zone -40 ℃ low temperature impact toughness gradually increased, when the CO2 content increased from 4% to 10%, the low temperature toughness increases greatly, with the further increase of CO2 content, the low temperature toughness increases tend to be gentle.