The effects of mix activated fluxes on the penetrations, microstructures and mechanical properties of tungsten inert gas (TIG) welded AZ31 magnesium alloy joints were studied. The results showed that an increase in the amount of TiO2 coating improved the weld penetration and depth/width ratio of the TIG welded AZ31 magnesium alloy seams. The α-Mg grains of the fusion zone (FZ) became fine gradually with the addition of CaF2 coating but coarsened sharply when the amount of TiO2 coating was over 70%. In addition, the porosities and total length of solidification cracks in the FZ were reduced by the CaF2 and TiO2 coatings. The ultimate tensile strength value of the welded joints increased with the addition of TiO2 coating but decreased sharply when more TiO2 coating was adopted.

Effects of mix activated fluxes coating on microstructures and mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joints

Active flux TIG (ATIG) welding is a simple variant of the conventional TIG process that allows increased penetration of the weld and enables welding in one pass, with total penetration and without chamfer opening, for joints with thicknesses of 5 mm or more. Different mechanisms have been proposed to explain this effect, with emphasis on contraction of the arc due to the presence of negative ions and alteration in the movement of liquid metal in the weld pool, associated with variations of surface tension as a function of temperature. This study evaluates the effect of the amount of one flux of one component (Cr2O3) placed on the surface of the work piece, and the additions of KClO4 and Al2O3, on the shape of the weld bead. Three sets of bead-on-plate weld tests were performed on 5-mm-thick ABNT 304 stainless steel plates. In the first set, the amount of flux used varied; in the second set, the effect of the additions of KClO4 was studied; and in the third, Al2O3. Electric current and voltage were measure...

Effect of flux density and the presence of additives in ATIG welding of austenitic stainless steel

Gas tungsten arc welding is a popular process in those applications requiring a high degree of quality and accuracy. However, this process has a big disadvantage against the substantially high productivity welding procedures. Hence, many efforts have been made to improve its productivity. One of these efforts is the use of activating flux (A-TIG welding). In this study, the performance of A-TIG welding on 304L austenitic stainless steel plates has been presented. Two oxide fluxes, TiO 2 and SiO 2 were used to investigate the effect of A-TIG welding process on weld morphology, microstructure and mechanical properties of weldments. The experimental results indicated that A-TIG welding could increase the weld penetration and depth-to-wide ratio. It was also found that A-TIG welding could increase the delta-ferrite content of weld metals and improve the mechanical properties. Moreover, a 2D axial symmetric model was developed to simulate the flow behavior in the melting pool. These results were compared to those experiments carried out on a stainless steel (304L) melted by a stationary heat source.

https://www.issiran.com/public/files/isij/No.17/2013-5.pdf

Welding of 304l stainless steel with activated tungsten inert gas process (a-tig)

The effects of fluxes and the size of SiC particles on the morphologies, microstructures and mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joints were investigated. The results showed that addition of SiC particles in the activating fluxes led to the decrease in all the weld penetrations while the surface appearance of welded joints improved in the case of TiO2 activating flux was adopted. Grain refinement was obtained in the welded seams with the addition of SiC particles in TiO2 flux and the effect of nanosized SiC particles on grain refinement is found to be more impressive than that of microsized SiC particles. The microhardness of the fusion zone and ultimate tensile strength of the welded joints increased with the addition of SiC particles in TiO2 activating flux and nanosized particles have more strong efficiency on the improvement of mechanical properties compared with microsized SiC particles. SiC particles did not improve the mechanical properties of A-TIG welde...

Effects of fluxes on distribution of SiC particles and microstructures and mechanical properties of nanoparticles strengthening A-TIG (NSA-TIG) welded magnesium alloy joints

TIG welding has high levels of stability and permits more refined control than the majority of other arc welding processes. However, it is well known that small changes in the chemical composition of the base metal and arc operating region can have a pronounced effect on the resulting weld bead shape, which reduces the ability to control and predict the process. Obviously, this reduces the reliability and controllability of TIG welding. This study reviews the variability of weld beads obtained in the TIG process, with small changes in chemical composition of the base metal, and A-TIG and TIG weldings with active gas. Aspects that are similar and unique to each case are highlighted and discussed. The mechanisms of weld bead shape presented in the literature are also presented and compared.

The chemistry of TIG weld bead formation

在焊接弧上激活流动的效果被调查。water-cooling 系统和不锈钢的一个特殊集合被用作父母材料。在焊接过程期间，高速度的照相机系统和示波器被用于分别地捕获即时弧形状和弧电压。试验性的结果显示 SiO2 流动能增加弧电压。当 TiO2 没在弧电压上有这效果时。与常规钨相比焊接的惰性的气体(C-TIG ) ，焊接的 A-TIG 的弧形状与 SiO2 流动使用了，这被发现显然变化了。

王新洪

Papers

Effect of activating flux on arc shape and arc voltage in tungsten inert gas welding