厚板钛合金磁控窄间隙TIG焊接技术发展现状

磁控窄间隙TIG焊接技术能有效解决厚板钛合金侧壁熔合不良的问题,其工艺稳定性好、设备成本较低,能为大型钛合金海工结构和装备制造提供有力支撑。围绕厚板钛合金磁控窄间隙TIG焊接技术及其研究现状展开论述。重点阐述了外加横向磁场对电弧摆动的作用机理,并讨论了主要焊接工艺参数(窄间隙坡口设计、焊接电流强度、外加磁场强度和频率及电极位置)对焊缝成形的影响。结合自研结果探讨了不同规格钛合金磁控窄间隙TIG焊接接头的显微组织和力学性能,并进一步概述了焊后残余应力分布特征。研究结果表明,利用外加磁场实现电弧周期摆动能有效调控热输入分布,进而改善侧壁熔合不良的问题;相比其他窄间隙焊接技术,磁控窄间隙TIG焊接能获得更加均匀的焊缝组织和优异的接头力学性能;磁控窄间隙TIG焊接后,接头表面存在较大拉应力,结合合适的热处理工艺能有效降低接头残余应力。最后,对磁控窄间隙TIG焊技术发展和前景进行了展望。

Progress in Magnetically-controlled Narrow-gap TIG Welding of Thick-plate Titanium Alloys

Magnetically-controlled narrow-gap TIG (NG-TIG) welding can effectively solve the problem of poor sidewalls fusion of thick-plate titanium alloys. Additionally, due to the excellent stability and low equipment cost, this welding process can make a strong contribution to the manufacturing of large marine structures and equipment made up by titanium alloys. This paper reviewed recent advances in magnetically-controlled NG-TIG welding technology of thick-plate titanium alloys. The influences of external transverse magnetic field on arc oscillation were elaborated. Impacts of welding process parameters, including the design of narrow gap groove, welding current intensity, intensity and frequency of external magnetic field and electrode position, on formation of weld seam were discussed systematically. The microstructure and mechanical properties of different titanium alloys joints fabricated by magnetically-controlled NG-TIG welding were also investigated based on obtained results. Then, the residual stress distribution induced by welding was further explored. The results showed that the external transverse magnetic field can effectively regulate the distribution of heat input of arc and overcome the problem of poor sidewall fusion. Compared with other narrow-gap welding techniques, magnetically-controlled NG-TIG welding can obtain more uniform seam microstructure and excellent joint mechanical properties. Magnetically-controlled NG-TIG welding caused remarkable tensile residual stress on the joint surface. The residual stress can be effectively reduced through appropriate post-welding heat treatment. Finally, the development and prospect of magnetically-controlled NG-TIG welding technology were prospected.