I.U. Abhulimen Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 8( Version 4), August 2014, pp.31-40 www.ijera.com 31 | Page Prediction of Weld Quality of A Tungsten Inertr Gas Welded Mild Steel Pipe Joint Using Response Surface Methodology (Rsm) 1 I.U. Abhulimen, 2 J.I. Achebo 1 Department of Materials and Production Engineering, Faculty of Engineering and Technology, Ambrose Alli University Ekpoma, Edo State, Nigeria. 2 Department of Production Engineering, Faculty of Engineering, University of Benin, Benin City, Edo State, Nigeria ABSTRACT The weld quality of tungsten inert gas (TIG) welded joint has been investigated to identify the most economical weld parameters that will bring about optimum properties. Response surface methodology has been used in the optimization of the tungsten inert gas weld of mild steel pipes. Response surface methodology, based on the central composite face centered design was generated for the purpose of optimization of the weld quality.All the process parameters have desirability of 1. Tensile strength response for this solution have a desirability of 0.910595 and the yield strength of 0.59. Result showed that minimizing current and voltage an average tensile strength of 535.452MPa and yield strength of up to 408.74MPa can be achieved, while keeping gas flow rate and electrode diameter within the range of test. It was also deduced that tensile elongation of the TIG weld is not influenced by the process parameters selected for the purpose of this study. KEYWORDS: Flow, Methodology, Optimization, Rate, Tungston. I. INTRODUCTION Oil and gas pipelines are among the biggest infrastructure projects in developing countries in recent years. Because mild steel is available in a variety of structural shapes and are easily welded into pipe, tube, tubing etc., they are used for pipelines in the oil and gas industries. Mild steel pipes and tubing are easy to fabricate, readily available, and relatively cheaper than other metals.TIG welding (Tungsten Inert Gas Welding) is also known as Gas Tungsten Arc Welding (GTAW) which uses a non-consumable electrode and separate filler metal with an inert shielding gas.TIG welding, is about the most popular welding method, which finds its applications in industrial environments. Evolving microstructure of welds in turn depends on the heating cycle arising during the welding, composition of the welded alloy, cooling condition, and the filler material.The prevailing heating cycle during welding is dependent on factors such as current, speed, electrode diameter, gas flow rate, voltage etc. making welding a multi- input, multi-output process.A common problem that has faced the pipeline engineer is the control of the process input parameters to obtain a good welded joint with the required bead geometry and weld quality with minimal detrimental residual stresses and distortion. Response Surface Methodology (RSM)was used to obtain optimum model to predict the output quality of the weld. This was important because it explores the relationships between several explanatory variables and one or more response variables. (Box and Wilson 1951). The main idea of RSM is to use a sequence of designed experiments to obtain an optimal response. II. LITERATURE REVIEW Gunaraj et al (1999) designed a response surface methodology to determine and represent the cause and effect relationship between true mean responses and input control variables influencing the responses as a two or three dimensional hyper surface. Jayachandran and Murugan (2011) carried out investigations on the Influence of surfacing process parameters over bead properties during stainless steel cladding and discovered that an optimum weld cladding process yields minimum base metal dilution with higher deposition rates with the required cladding thickness in minimum number of passes. Krishankant et al (2012) used the application of response surface modeling for determination of flux consumption in submerged arc welding by the effect of various welding parameters direct and interactive effects of process variables on the bead parameters through two dimensional and three dimensional graphs. Kundan et al 2012, showed that tungsten inert gas welding (TIG) is one of the most important material joining processes widely used in industry. Surface Response Methodology has been developed to study the effects of input variable (i.e. current, voltage, travel speed) on output responses (i.e. reinforcement height, weld bead width, metal deposition rate). Elangovan et al, 2012 showed how an effective methodology was developed to determine the optimum welding conditions that RESEARCH ARTICLE OPEN ACCESS brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Directory of Open Access Journals