分离电弧AA-TIG焊焊缝组织及性能

Weld structure and property of separation arc AA-TIG welding

分离电弧AA-TIG焊(arc assisted activating TIG welding)是一种新型高效的焊接方法,该方法利用辅助电弧在待焊焊道表面预熔生成一道氧化层,再进行普通TIG焊,可显著增加焊缝熔深.通过改变辅助电弧中活性混合气体O2的含量,研究焊缝组织及性能与O2引入量的关系.结果表明:焊缝组织为奥氏体及少量的铁素体,铁素体中还析出了σ相.焊缝的抗拉强度与母材相近.当O2引入量超过2L.min-1时,焊缝的低温冲击韧性降低较多,这与焊缝中铁素体增多,析出的σ相增加以及形成氧化物夹渣有关.

Separation arc AA-TIG is a novel and efficient welding method, where an oxide layer is premelded on weld position with assisting arc and Ar＋O2 shield gas, and then the conventional TIG welding is conducted. This process can significantly increase the depth of molten weld. By changing the content of oxygen in active mixed gas the relationship of the structure and property of the weld to the introduced quantity of oxygen was investigated. The result showed that the structure of weld would be of austenite, small amount of ferrite and o-phase separating out of the ferrite. The tensile strength of weld was similar to the base metal. The low-temperature impact tenacity would decrease more greatly when the introduced quantity of O3 was more than 2 L/min, due to ferrite increasing in the weld, separated σ-phase increasing, and oxide slag forming.