Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field

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GRD Journals- Global Research and Development Journal for Engineering | Volume 5 | Issue 11 | October 2020 ISSN- 2455-5703

Experimental and Theoretical Investigation into the Effect of Welding-Parameters and MagneticField on Structure and Properties of Weld in Arc-Welding Rudra Pratap Singh Department of Mechanical Engineering I.E.T., G.L.A. University Mathura, (U.P.)

Abstract This paper investigated the multi-response optimization of shielded metal arc welding (SMAW) process for an optimal parametric combination to yield favorable bead geometry and mechanical properties of welded joints using artificial neural networks method. Total twenty five sets of experimental input output data were obtained to train the ANN model and to verify the prediction made by the model. Cross slide of a lathe machine was used to have constant welding speed. External magnetic field was obtained with the help of a bar magnet mounted on tailstock side of the lathe machine with a wooden structure. The main aim was to derive objective functions like welding current, voltage, speed of welding and external magnetic field to be optimized within experimental domain. The objective functions have been selected in relation to parameters of SMAW welding bead geometries like bead width, reinforcement height, depth of penetration, and mechanical properties like hardness, impact strength and tensile strength. The model was trained with the help of eighteen sets of data. Optimal results have been verified through seven other data sets of experiments. This shows application feasibility of the artificial neural networks for continuous improvement in product quality in manufacturing industry. Keywords- Back Propagation, Bead Geometry, External Magnetic Field, Input Process Parameters, Mechanical Properties, Neurons

I. INTRODUCTION The advantages of welding, as a joining process, include high joint efficiency, simple set up, flexibility and low fabrication costs [1]. Shielded metal arc welding is a versatile and flexible process requiring simple equipment, a skilled welder, welderâ€&#x;s accessories and electrodes. Welding can be done in all positions, both in shop and at site. Welded joints of sound quality and adequate mechanical properties can be obtained by using correctly designed electrodes and proper welding procedures. The process is intermittent, because welding has to be interrupted from time to time to discard the unused stub and to place a fresh electrode into the holder, and also to deslag the joint. For higher productivity, semi-automatic or fully-automatic welding processes are preferred [2]. The mechanical strength of weld is influenced not only by the composition of the metal, but also by the weld bead shape. The current, voltage, welding speed and polarity can influence the bead shape and size [3]. Due to the effect of external longitudinal magnetic field the weld bead becomes wider. Usually, the wider the nugget diameter is, the better the mechanical performance of the weld will be [4]. External magnetic field can produce electromagnetic stirring (EMS). EMS is considered as an effective way to control the weld quality of SMAW at a relatively low cost with high efficiency. The principle of EMS is the use of Lorentz force, which derives from the interactions of welding current and the externally applied magnetic field. During the welding process, the molten metal driven by the Lorentz force makes high-speed movement and eventually affects the melting and solidification process. EMS technique can successfully be applied in arc welding by affecting the shape of weld pool and refining crystal grains [5]. The weld quality is achievable by meeting quality requirements such as bead geometry which is highly influenced by various process parameters involved in the process. The weld bead geometry plays an important role in determining the mechanical properties of the weld. Hence the input welding process variables which influence the bead geometry must properly be selected to obtain an acceptable high quality joint [6]. Generally welded joints are the locations for the crack initiation due to inherent metallurgical, geometrical defects as well as heterogeneity in mechanical properties and presence of residual stresses. For maintaining structural integrity of welded structures throughout the service life of the structure, relationship between welding process, properties and performance of the structure should be well-understood and established. Several studies and researches have been conducted so far to determine the effect of welding parameters on weld properties and quality. Heat input affects the weld mechanical properties for SMAW process [7]. Investigation into the relationship between the welding process parameters and bead geometry began in the mid 1900s and regression analysis was applied to welding geometry research [8]. An ANN model can be developed successfully to All rights reserved by www.grdjournals.com

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