1 | Page OPTIMIZATION OF PROCESS PARAMETERS IN SUBMERGED ARC WELDING OF PIPE-JOINT USING MILD STEEL IS: 1079, GR.O BY TAGUCHI METHOD Goutam Biswas 1 , Prof. Debasish Roy 2 and Prof. Arpan Kumar Mondal 3 1 Mechanical Engineering Dept., Jadavpur University, Kolkata-700032, WB, India, email: findgoutambiswas@gmail.com 2 Mechanical Engineering Dept., Jadavpur University, Kol-700032, WB, India, email: debasish_kr@yahoo.co.in 3 Mechanical Engineering Dept., NITTTR, Kolkata, Salt-Lake, Kol-700106, WB, India, email: arpan@nitttrkol.ac.in Abstract Submerged Arc Welding (SAW) process is a conventional fusion welding process in the manufacturing industries. Quality of welded joint, an important issue, is largely influenced by the proper selection of process parameters for obtaining sound weld. In the present research, welding current, welding voltage, welding speed and electrode stick-out are treated as process parameters with different levels viz. (I=250-265-267amp),(V=23-24-25volt),(St= 0.7-0.6-0.87m/min) with (ES=25-25-25mm) and the quality of the joint is assessed in terms of ultimate tensile strength and hardness. In this work, two mild steel (Mild Steel IS: 1079, Gr.O) pipe-segments of thickness 5mm and length 100 mm were joined through this welding. Taguchi's L9 orthogonal array was used for design of experiment purpose (DOE). Taguchi technique was applied to study the parametric effect on the responses serving as objective functions subject to optimization. Taguchi-Quality-loss-function is considered to obtain the optimized values of the quality characteristics within the well-defined experimental domain. Signal to Noise ratio(S/N) was computed to evaluate the optimal process parameters most significantly dominant for detecting weld-quality. Percentage contribution (%C) of each parameter is evaluated on performance characteristics. Based on the experimental results and analysis, some conclusions were inferred. Keyword: SAW; ANOVA; S/N; Taguchi Method; Process Parameters 1. INTRODUCTION Submerged Arc Welding process is automated and semi-automated high deposition down hand welding process, not vertical or over welding process. The distinguishing feature of this welding process is that arc is covered under the heap of incoming flux. Weld pool is fully submerged, heat loss is minimum and thermal efficiency is very high~80% − 90%   . A constant current/constant voltage power source is required in order to control wire feed rate, constant voltage power supplies, digital control panel, which provides precise control of welding process parameters. Due to its higher deposition rate, SAW process has become popular in large structural application such as fabrication of Ships, Pressure vessel, Bridge beam, Massive water pipes, Penstocks, Boiler, Railroad, Automobile, Aviation and Nuclear Industries, etc. In Submerged Arc Welding, heat is generated by an electric arc in between a bare consumable electrode wire and the work- piece. Since the welding arc and the weld pool are completely submerged under the blanket of fresh and fusible flux, hence arc is not visible. So this process is called Submerged Arc Welding process. During welding, the granular flux coming from the hopper is melted with the help of the heat input from the arc and forms molten flux layer reducing the tendency of spatter. Components of SAW system: Usually, SAW is a high current density (≥ 1000 ) welding process as it is used to join heavy sections and thick plates due to its high penetration depth, high deposition rate and high welding speed are possible as the developed electric arc and the molten weld pool is concealed under the layer of fusible granular flux coming from the hopper. The main components of SAW system is depicted in the following figure. The different elements consisting the circuit are namely Flux hopper, Flux flowing rubber hose, Electrode wire bobbin, Copper