Parametric optimization of activated-TIG welding of hot rolled steel (IS 5986) using taguchi method
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Date
2022-10
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G. B. Pant University of Agriculture and Technology, Pantnagar
Abstract
The present investigation aims to optimized & develop input parameters for joining of Hot rolled steel using activated tungsten inert gas (A-TIG) welding process. Three combinations of fluxes were prepared to decide suitable flux for Hot rolled steel. The design of experiment was carried out for optimization of welding parameters to achieve the desired depth of penetration. The square butt weld joints were fabricated on 8 mm thick plates employing A-TIG welding using developed flux and optimized process parameters employing single side welding procedure. The Ultimate Tensile testing hardness test and impact tests were carried out on the base metal and weld joint. The strengths, ductility and impact toughness of the joints were found to be comparable with that of the base metal. Gas Tungsten Arc Welding (GTAW), also called Tungsten Inert Gas welding (TIG) is one of the main welding methods which have been widely used in industries for the welding of stainless steel, titanium alloy, and other nonferrous metals for its high weld quality and lower equipment Investment. The major limitation of TIG welding of steel is mainly the limited thickness of material which can be welded in a single pass and that has a lower production rate. Therefore, enhancements in the depth of penetration in weld bead have long been sought in steel weldments produced by TIG welding process. These limitations have been overcome by introducing oxide powders at the joint during the TIG welding process which is called Activated Tungsten Inert Gas Welding (A-TIG). Hot rolled steel is used in a range of automobile products it has excellent forming and welding characteristics. Post-weld annealing is not required when welding thin sections. It has excellent corrosion resistance in a wide range of atmospheric environments and many corrosive media. In the present work, TIG Welding was carried out on Hot Rolled steel plates of 8 mm thickness. In the first phase, the specimens were welded as bead on plate. The Taguchi method is the technique is used to determine the level of influence of the independent variables on the dependent variables. The independent variables have been taken for this study are 5 of welding parameters,viz three different types of flux composition combination of two compound TiO2 And SiO2 flux, three set of welding voltage, welding current, gas flow rate, root gap is used. The dependent variables are tensile strength (TS), Hardness (HR), Impact strength (IS), Depth of Penetration (DP), Bead Width (BW), of the weld morphology are used. The SEM images of the macro structures of weld morphology were compared. The results obtained from the macro structures of weld morphology indicated that the higher depth of penetration has been achieved in the specimens welded with A-TIG welding process when compared with Conventional TIG welding process. The results obtained from the Taguchi, L27 O.A. technique indicated that the activating flux showed the maximum percentage of contribution in weld morphology. In Next phase of this study was to determine the influence of two component fluxes on the weld morphology of A-TIG weldments of Hot Rolled steel plates. The activating fluxes such as TiO2 & SiO2, were applied with different proportions to the specimens. Experimental results indicated that using 60% TiO2 +40% SiO2 flux combination leads to a significant increase in joint penetration and the aspect ratio.