Optimization of CA-TIG welding parameters to predict and maximize tensile properties of super alloy 718 sheets for gas turbine applications

Purpose The primary objective of this investigation is to optimize the constricted arc tungsten inert gas (CA-TIG) welding parameters specifically welding current (WC), arc constriction current (ACC), ACC frequency (ACCF) and CA traverse speed to maximize the tensile properties of thin Inconel 718 sheets (2 mm thick) using a statistical technique of response surface methodology and desirability function for gas turbine engine applications. Design/methodology/approach The four factor – five level central composite design (4 × 5 – CCD) matrix pertaining to the minimum number of experiments was chosen in this investigation for designing the experimental matrix. The techniques of numerical and graphical optimization were used to find the optimal conditions of CA-TIG welding parameters. Findings The thin sheets of Inconel 718 (2 mm thick) can be welded successfully using CA-TIG welding process without any defects. The joints welded using optimized conditions of CA-TIG welding parameters showed maximum of 99.20%, 94.45% and 73.5% of base metal tensile strength, yield strength and elongation. Originality/value The joints made using optimized CA-TIG welding parameters disclosed 99.20% joint efficiency which is comparatively 20%–30% superior than conventional TIG welding process and comparable to costly electron beam welding and laser beam welding processes. The parametric mathematical equations were designed to predict the tensile properties of Inconel 718 joints accurately with a confidence level of 95% and less than 4.5% error. The mathematical relationships were also developed to predict the tensile properties of joints from the grain size (secondary dendritic arm spacing-SDAS) of fusion zone microstructure.

Sustainable Analysis of Process Parameters during TIG welding of dissimilar joining between 304 Stainless Steel and AISI 1018 Mild Steel

The present work investigates TIG in terms of strength and energy consumption during joining of dissimilar metal plates between 304 Stainless Steel and AISI 1018 Mild Steel. TIG welding basically promotes a sustainable environment because it consumes less energy. Energy conservation means to reduce imbalance between demand and energy supply that is necessary to protect ecological resources and natural environment. TIG welding is a precision welding process which makes possible for joining of thinner and lighter materials. Joining of various dissimilar metals becomes great interest owing to the different challenges that are posed by deviation in the material composition as well as the characteristics of the joined metals. The main objective is to optimize energy consumption and tensile strength by taking effective process parameters that are Current, Travel Speed and Gas Flow Rate and also determination of main influential process parameters on energy consumption and tensile strength by using Taguchi method. Contour plot has also been shown in this present investigation.