TA2薄壁钛管双TIG焊温度场和残余应力分布对接头组织性能的影响

Influence of temperature field and residual stress distribution on microstructure and properties of pure titanium TA2 thin-walled pipe by tandem TIG welding

针对纯钛TA2薄壁管的钨极氩弧焊(TIG)高速焊接时出现的咬边、驼峰等成形缺陷,以及焊接效率低等问题,提出采用双TIG焊接工艺,可有效提高焊接速度,改善焊缝成形的解决措施。同时采用ABAQUS对两种焊接方法建立焊接热弹塑性有限元模型,对比分析焊接温度场和焊后残余应力分布,并进一步对焊接TA2薄壁钛管进行显微组织分析及力学性能测试。试验结果表明:模拟所得的两种接头的焊缝轮廓尺寸与实际接头相近,双TIG焊接时焊缝中心温度低于TIG焊接,且双TIG焊缝附近Von Mises应力大于200 MPa的宽度小于TIG焊缝,焊后稳态时焊缝中心的Von Mises应力相近。双TIG焊缝中心及热影响区显微组织比TIG焊细小,两种接头的各项力学性能和耐海水腐蚀性能均满足相关标准要求。φ19 mm×0.7 mm的TA2钛管在获得良好焊缝成形的条件下,采用双TIG焊接工艺的焊接速度可达5 m/min。与TIG焊接工艺相比,生产效率大为提高,基本实现焊缝零缺陷。

Aiming at the low welding efficiency and defects such as undercut and hump in the tungsten inert gas welding(TIG)of pure titanium TA2 thin walled pipe,the tandem TIG welding process is proposed,which can effectively increase the welding speed and improve the appearance of weld.The ABAQUS software is used to build welding thermal elastic-plastic finite element model for the two kinds of welding methods,and the welding temperature field and residual stress field are compared and analyzed.The microstructure analysis and mechanical properties test of welded joints are carried out.The results show that the weld contour sizes of the two simulated joints are similar to the actual joint and the weld center temperature of tandem TIG is lower than that of TIG.The width of Von Mises stress range above 200 MPa around tandem TIG is less than that of TIG,and the values of Von Mises stress in weld center are similar.The microstructure of the weld center and HAZ of tandem TIG is smaller than that of TIG,and the mechanical properties and corrosion resistance of the two joints meet the requirements of relevant standards.Under the conditions that the pure titanium TA2 pipe with a specification ofΦ19 mm×0.7 mm obtains good appearance of weld,the welding speed by tandem TIG welding can reach 5 m/min.Comparing with TIG,the tandem TIG welding can highly improve production efficiency and basically accomplish no defect of straight weld.