厚壁焊接钛管的等离子填丝+脉冲TIG双枪焊接工艺研究

钛及钛合金厚壁焊管是海水淡化和海洋工程等行业的主要部件。采用前置直流等离子填丝+后置脉冲TIG电弧的双枪焊法,无耦合的等离子焊+TIG焊形式利用等离子弧焊与TIG焊的优点实现了大口径壁厚4 mm的TA1焊接钛管的优质、稳定焊接。结果表明,随着等离子气体流量的增加,直流等离子填丝焊的熔深增加,厚壁钛管全熔透;后置TIG电弧对已形成焊缝进行重熔,TIG焊脉冲频率的增加可以降低焊缝晶粒尺寸,提高接头性能,并对前置等离子填丝焊过程出现的咬边等缺陷具有较好的修复作用。本方法不但扩大了焊缝成形的工艺窗口,而且焊接过程稳定,接头抗拉强度达到354 MPa,经实际生产验证,实现了厚壁焊接钛管的低成本优质焊接生产。

Study on the thick titanium tube welded by wirefeeding plasma arc+pulsed TIG method

Titanium and titanium alloy thick-wall welded tubes are the main components in industries such as seawater desalination and marine engineering.In this paper,the double gun welding method of front DC plasma filler wire welding+post pulse TIG arc is used to explore the high-quality and stable welding process of TA1 welding titanium tube with thickness of 4 mm.The non-coupling plasma welding+TIG welding forms utilize the advantages of plasma arc welding and TIG welding respectively.The results show that with the increase of plasma gas flow rate,the penetration depth of DC plasma wire-filled welding increases,which can achieve good full penetration welding of thick-walled titanium tubes;the rear TIG arc remelts the formed weld seam.With the increasing of TIG welding pulse frequency,the grain size of weld and heat affected zone is reduced,meanwhile the joint performance is also improved.The repairing effect on defects such as undercuts during the pre-plasma wire filler welding process is significantly improved by rear TIG arc.This method not only expands the process window for qualified appearance of weld,but also stabilizes the welding process.The joint strength reaches 354 MPa.Through actual production verification,low-cost high-quality welding production of thick titanium welding tube is realized.