iesl/pub/guide 1 ENGINEER Optimization of Shielded Metal Arc Welding (SMAW) process for mild steel L. S. Sisira K Weerasekralage, M. Karunarathne, S. D. Pathirana Abstract: Shielded Metal Arc Welding (SMAW) or the conventional arc welding process is particularly dominant in structural joints, pressure vessels and in maintenance and repair work. This process is widely used in many industrial applications due to its versatility, simplicity and indoor and outdoor applicability. A certain level of operational skills is needed in performing the SMAW process in order to obtain a quality weldment. Further, input process parameters such as current, voltage, arc gap, welding speed, electrode orientation, etc. play a vital role in the quality of the weldment. This research especially addresses and simulate mild steel in arc welding, covering industrial applications including small scale industries. The study investigates the influence of different input process parameters on weld quality through mechanical tests and verified through microstructural examinations. Further, authors wish to identify the optimized process variables in obtaining quality weldment at minimum cost for real industrial applications. For the study, thirty-six number of welded samples of mild steel were selected based on a full factorial array, Taguchi’s orthogonal array, welding standards, power source specifications and deviations based on trial experiment. According to the planned experimental procedure, three types of mechanical tests (hardness, toughness and tensile) followed by the microstructural tests were carried out. Results of the investigation revealed that the 12 th , 9 th and 11 th sample sets with corresponding input parameters had produced the best quality weldments. As their joint characteristics, tensile properties are better with poor impact toughness compared to the base metal Keywords: Arc Welding, SMAW, Optimization, Mechanical tests, Microstructure 1. Introduction It is the objective of this study to identify the optimum welding parameters for the manual SMAW process in order to facilitate the industrial applications for better quality weldments. Especially this research addresses and simulates commonly mild steel in arc welding, covering industrial applications including small scale industries. An investigation was carried out to establish the concept by selecting welding current, voltage and groove angle as input welding parameters [1][2]. As per SMAW process optimization, hardness, toughness/impact strength and tensile strength were determined and analyzed experimentally in customizing industrial application with the intended purpose [3][[4][[5]. Further, it is important and possible to improve process optimization continuously with different software developed with data acquisition systems (DAC for big data) in formulating optimized algorithms [6][7]. Selection of an arc welding process is complex with respect to the workpiece, application, simplicity, infrastructure, cost, expected quality, etc. Therefore, particular welding application is performed with the interaction of many factors and attributes as shown in Figure 1. In this regard, the arrangement of Shielded Metal Arc Welding (SMAW) process is chosen in the industry due to its simplicity as few process-attributes such as workpiece, welder, power source and electrode make the set up complete. It is an effective and low-cost process for producing quality products [8]. Application of SMAW or Manual Metal Arc Welding (MMAW) is gradually replaced in the global context with the introduction of new processes while it is very important for developing countries with low-cost infrastructure, simplicity and availability of human capital [7]. The shielded metal arc welding is most widely used in small scale industries, because of its low cost, simplicity, flexibility and portability [10]. Further, manual welding still occupies a leading position in domestic, maintenance, fabrication and offshore applications [3]. Special advantages of Shielded Metal Arc Welding (SMAW) process are the improved microstructure at the welded joint by varying L. S. Sisira K. Weerasekaralage BTech(Mech Eng)(OUSL), MSc Eng (Peradeniya) Mechanical Engineer/Lecturer,Faculty of Eng, SLIIT. Dr. M. Karunarathne B.Sc. Eng. (Moratuwa), PhD (Cambridge) Head Dept of Material Eng, Faculty of Eng, SLIIT Eng.(Prof.) S.D.Pathirana BScEng (Perdeniya), MSc, PhD, MASME, MIEEE, CEng. MIET & FIE(SL), Professor of Production Engineering, University of Peradeniya.