粉末熔池耦合活性TIG焊接方法

提出了一种新型活性焊接方法——粉末熔池耦合活性TIG焊(Powder pool coupled activating TIG welding,PPCATIG)。该方法采用双层气体进行焊接,内层利用惰性气体保护钨极,外层通过自动送粉装置将活性剂粉末随保护气体送入电弧-熔池区域,增加熔深,提高焊接效率,实现机械化自动化焊接。针对SUS304不锈钢进行了直流正接PPCA-TIG表面熔深,通过与传统TIG焊对比,研究了SiO_2活性剂对电弧形态、焊缝成形、组织和力学性能的影响。结果表明:SiO_2能使电弧等离子体收缩、熔池金属流态改变,并且焊缝熔深能达到传统TIG焊的3倍以上,焊接效率明显提高。焊缝组织主要为奥氏体和铁素体,铁素体形态以骨架状为主。焊缝抗拉强度略低于母材,但相比传统TIG焊,焊缝屈服强度略有提高,其焊缝低温冲击韧性达到了传统TIG焊的96.8%,表现出了良好的力学性能。同时,采用该方法可有效避免活性剂粉末对钨极的污染。

Powder Pool Coupled Activating TIG Welding Method

The present work aims to develop and display a novel activating welding method, i.e. powder pool coupled activating TIG (PPCA-TIG) welding. Amongst the PPCA-TIG welding, tungsten was protected by inner layer argon or other inert gas, meanwhile the activated flux powder mixing protective gas was transported into the outer layer of arc-molten pool area by the automatic powder feeding device to realize the aim of increasing the depth of penetration, improving the welding efficiency and welding mechanization and automatization. Based on the SUS304 stainless steel, the conventional DC TIG welding and SiO₂ activated flux of DC PPCA-TIG welding were performed, and then the effect of SiO₂ flux on the arc morphology, weld appearance of welding process, microstructure and the mechanical properties were studied. The results show that SiO₂ can constrict the arc plasma, change the weld pool fluid flow mode and augment the depth of weld penetration to 3 times more than that of the conventional TIG welding, and the welding efficiency is obviously improved. The microstructure of the weld is mainly consist of austenite and ferrite, the ferrite morphology is mainly skeleton. Weld tensile strength is slightly lower than that of the base metal, while compared with the conventional TIG welding, it improves the yield strength slightly, and the lower temperature impact toughness of the weld is 96.8% of TIG weld, which shows favorable mechanical properties. At the same time, the PPCA-TIG method can effectively avoid the pollution on the tungsten electrode from the activated flux powder.