铝合金活性TIG焊熔池表面化学反应分析

Analysis of chemical reaction on weld pool surface in activating TIG welding of aluminum alloys

针对铝合金交流A-TIG焊、FB-TIG焊和FZ-TIG焊,研究活性剂与熔池表面金属或表面氧化膜之间的化学反应,对于确定这些焊接方法的可行性和指导活性剂配方开发具有重要意义.通过焊缝表面焊渣XRD分析,并采用物质吉布斯自由能函数法进行反应热力学计算分析了熔池表面发生的化学反应.发现采用FZ108+SiO2的FZ-TIG焊发生了活性剂FZ108与熔池金属之间的吸热反应,能起到收缩电弧增加熔深的作用;对于采用FZ108的A-TIG焊,反应所吸收或放出的热量少,对收缩电弧的作用也很小;对于采用SiO2的FB-TIG焊,未发生活性剂与熔池金属和表面氧化膜之间的化学反应,不会通过该反应过程影响电弧.

For activating TIG welding of aluminum alloys,including A-TIG welding,FB-TIG welding and FZ-TIG welding,the analysis of chemical reaction between the activating fluxes and the weld pool metal has great significance to certain the fea-sibility of these welding processes and instruct the developments of activating fluxes.Through the XRD analysis of weld surface slag,the chemical reaction thermodynamics was calculated based on functional determinant of Gibbs'Free Energy,and the chemi-cal reaction on welding pool was analyzed.It is found that,for the FZ-TIG welding,with multi-component flux FZ108 developed by authors as central region flux and SiO2 as outer region flux,the endothermic reactions between flux FZ108 and the welding pool metal can constrict the arc and increase weld penetration.For the A-TIG welding with flux FZ108,the few absorbed heat or the released heat of the chemical reactions has small influence on the arc.For the FB-TIG welding with flux SiO2,the chemical re-action between the flux and the weld pool metal and its surface oxide film does not happen,and the arc is not affected through these chemical reactions.