N. Rahimi, T. Saed,
Volume 5, Issue 2 (1-2020)
Abstract
In this study the effect of activating fluxes on the penetration depth, microstructure and microhardness of AISI316L austenitic stainless steel were evaluated by three TIG process variations (TIG, A-TIG and FB-TIG) and the results were compared together.. After selecting the optimal flux in the second stage, the effect of that on the penetration depth, microstructure and weld microhardness of welded 316L austenitic stainless steel by A–TIG and FB-TIG methods, were evaluated and the results were compared by the sample which was welded by TIG process. At this stage, it was found that the depth and width to depth ratio in FB-TIG method is slightly greater than the other two methods. Also in FB-TIG method, eqiaxed dendritic zone in the center line of weld is slightly greater than in A-TIG method. Study of microhardness of weld in three methods shows that in A-TIG and FB-TIG methods hardness of center line is more than TIG method.
A. Lori Amini, H. Sabet, M. Ghanbari Haghighi ,
Volume 6, Issue 2 (12-2020)
Abstract
In this investigation, the AISI 2205 duplex stainless steel was welded in the form of bead on plate by A-TIG process with different amount of the ZrO2 and TiO2 activated fluxes. The results of the visual inspection showed that the specimen with 50% ZrO2 and 50% TiO2 activated flux, had the lowest face width and the specimen with contains 90% ZrO2 activated flux, had the highest penetration depth. Also, the results showed that the angular distortion of the specimens with mix of the ZrO2 and TiO2 activated flux were 225% less than the specimen without activated flux. The results of macroscopic examination of different samples showed that the maximum length and width of the macroscopic grains were related to the sample with 90% ZrO2 activated flux and the smallest length and width of the macroscopic grains were related to the sample with 90% TiO2 activated flux. The hardness test results showed that the highest hardness of the samples was gained to 90% TiO2 activated flux specimen with 950 HV and the lowest hardness value for the sample with 90% ZrO2 activated flux with 410 HV. The results of all tests showed that surface activated fluxes (ZrO2 and TiO2) affected to the depth of penetration, face width, angular distortion, length and width of macroscopic grains and the hardness of weld metal by changing the longitudinal and transverse melt flow in the weld pool.
M. N. Sadraee Far, F. Kolahan,
Volume 9, Issue 2 (1-2024)
Abstract
In this study, we employed the active TIG method with ultrasonic vibration (UV) for welding 316L steel. Throughout the active tungsten inert gas (A-TIG) welding process, a high-frequency ultrasonic generator produced high-intensity acoustic waves at an optimal frequency of 20.3 kHz and a vibration amplitude of 8 micrometers. These waves were directed into the molten weld pool, covered by SiO2 nanoparticles serving as an activating flux. The effect of UV and nanoparticles on weld geometry and weld microstructure was analyzed and compared with conventional TIG welding proces. The results indicated that the use of nanopowder not only increased weld penetration by approximately 17.5% but also reduced the Weld Bead Width (WBW) by 28% compared to Conventional TIG. These values increased by 25% and decreased by 35%, respectively, in the presence of ultrasonic waves. Additionally, the introduction of nanomaterials into the molten pool led to finer grains. The ultrasonic waves played a crucial role in ensuring the uniform distribution of these nanomaterials in the melt, ultimately resulting in an enhanced microstructure of the weld.
