保护气体对Q690E双丝MAG焊焊缝组织性能的影响

Effects of Shielding Gas Composition on Microstructure and Property of Q690E HSLA Steel with Tandem Arc MAG Welding

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 high strength low alloy steel Q690E, adopting efficient twin-wire MAG welding robotic system, theeffects of shielding gas on the mechanical properties and microstructure of the weld metal were investigated. The results showthat the microstructure of the weld metal with 96%Ar＋4%CO2 （volume fraction） as shielding gas is mainly made up ofbainiteand martensite. When the content of CO2 in the shielding gas is 10% or 20%, the acicular ferrite of the microstructure of theweld metal increases. The best tensile strength of weld metal can be obtained with 10%CO： as shielding gas, and the leasttensile strength can be obtained with 20%CO2 as shielding gas. At the same time, along with the increase of CO2 from 4% to20% of the shielding gas, the - 40 ℃ low temperature toughness of the weld metal increases gradually.