American Journal of Materials Science 2016, 6(4A): 102-108 DOI: 10.5923/c.materials.201601.20 Influences of Process Parameters on Heat Affected Zone in Submerged Arc Welding of Low Carbon Steel Sailender M. 1,* , G. Chandra Mohan Reddy 2 , S. Venkatesh 3 1 ARDC, Hindustan Aeronautics Limited, Bangalore, India 2 Mahatma Gandhi Institute of Technology, Gandipet, Hyderabad, India 3 Department of Mechanical Engineering, University College of Engineering, Osmania University, Hyderabad, India Abstract Carbon steel is one of the most widely used materials in the industry for moderate and service requirements. For strong and continuous weld, widely used welding process in manufacturing industry is submerged arc welding (SAW). SAW has a large number of process parameters, act together in an intricate manner and influence the output performance. It is important in selecting process parameters to maintain the desired quality. The present work, parametric optimization of main parameters, such as open circuit voltage (OCV), wire feed rate (WFR), welding speed (WS) and nozzle-to-plate distance (NPD) and thereby to study influences on the output, heat affected zone (HAZ) of the weldments. Taguchi’s L 9 orthogonal array is been adopted to conduct experiments. The study is made by conducting experiments in ‘purging with gas’ condition and compared with ‘as weld’ experiments. The performance measure of control levels to select is observed through S/N ratio. The significance of the parameter and their contribution is calculated by ANOVA. Correlations are established between process parameters and performance outputs using regression analysis. Models developed and checked for their adequacy with the F-test, determined quantitatively and presented graphically. Validated models through confirmation tests and the predicted results are within the limits. Keywords Submerged Arc Welding, Taguchi, Analysis of Variance and Regression Models 1. Introduction Steel is one of the world’s most essential materials most widely used metals in our modern world and is fundamental to every aspect of our lives, from infrastructure to the humble tin-plated steel can that preserves food. It is strong, versatile durability, strength, affordable and infinitely recyclable [1]. ASTM A516 Gr.70 is a carbon-manganese steel and is suitable for the fabrication of welded pressure vessels designed for moderate and lower-temperature service, which require a continuous strong joint. Submerged arc welding (SAW) is one of the most widely used automatic welding process in manufacturing industry, due to deep penetration, smooth bead with high quality and reliability [2]. SAW has various notable input parameters and operating conditions, which influence together in an intricate manner on weld quality, physical characteristics as well as metallurgical characteristics [3]. It needs to be controlled to attain the required weld quality characteristics. Insufficient weld bead dimensions will cause to malfunction of the welded structure. The output responses in SAW are mainly influenced by parameters such as arc voltage, weld current, weld speed, * Corresponding author: sailumamu@gmail.com (Sailender M.) Published online at http://journal.sapub.org/materials Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved electrode feed and gap between weld plate & electrode. In many applications, engineers are facing the difficulty in predicting appropriate combinations of parameters to attain better weld quality. It requires number of experiments, which consumes time and expensive. To attain with better weld quality and to optimize the process parameters at a low cost, a designed experiment is the concurrent evaluation of two or more parameters for their ability to affect the resultant mean of particular process characteristics. Taguchi’s philosophy is an efficient tool and explained design of experiments (DOE) through parametric optimization of process [4]. Involves orthogonal arrays and systematize the parameters affecting the process, at which levels to be varied instead to test all combinations. Fisher [5] is made use of the factorial methods for achieving the interaction effects on response parameters through the statistically designed experiments. Robert et al. [6] are conferred with rich examples by means of actual engineering and scientific studies on experimentation strategy, data analysis and experimental results interpretation. The statistics, which is an integral component of experimentation, used to demonstrate the planning phase to the conclusions presentation. Douglas [7] enlightened the methods of descriptive statistics, the normal distribution and basics of confidence intervals and hypothesis testing for means and variance. Alberry et al. [8] are developed a computer program model for heat-affected zone (HAZ)’s for single and