氧化物活性剂增加镁合金熔深机理

为了研究活性剂对TIG焊焊接电弧形态的影响,采用单组分氧化物活性剂(Cr2O3、TiO2)进行AZ91D镁合金直流TIG焊接,由关系曲线得出Cr2O3和TiO2活性剂的最佳涂覆量分别为2.52和2.65 mg/cm2.采用高速摄像技术对A-TIG焊焊接电弧形态进行拍摄和记录,得到了涂覆单一活性剂的焊接电弧形态,并分析了电弧形态的变化机理.对比电弧形态照片可以发现:当无活性剂作用时,焊接电弧呈现出锥形;当有活性剂作用时,电弧呈现出收缩状态,且TiO2使电弧收缩的效果最为明显,Cr2O3次之.通过理论分析认为,电弧收缩理论和阳极斑点理论是氧化物活性剂增加熔深的主要机理.

Weld penetration increasing mechanism for magnesium alloy with oxide activating fluxes

To study the effect of activating fluxes on the TIG welding arc profile, the DC TIG welding of AZ91D magnesium alloy with single-component oxide activating fluxes such as Cr₂O₃ and TiO₂ was carried out. It is determined from the relation curves that the optimal coating amounts of Cr₂O₃ and TiO₂ activating fluxes are 2.52 mg/cm² and 2.65 mg/cm², respectively. The arc profiles of A-TIG welding were photographed and recorded by the high-speed camera technology, and the welding arc profiles of coating with the single oxide activating flux were obtained. In addition, the changing mechanism of arc profiles was analyzed. It can be found through comparing the photos of welding arc profiles that with no activating flux, the welding arc shows the cone shape. Under the action of activating fluxes, the welding arc shows the constriction state. Furthermore, the constriction degree of welding arc is more obvious with TiO₂, while that with Cr₂O₃ is followed. The theoretical analysis indicates that the arc contraction theory and anode spot theory are the main mechanisms of weld penetration increased by oxide activating fluxes.