DETERMINATION OF SAW PROCESS PARAMETERS USING OF EXPERIMENTS AND REGRESSION ANALYSIS

Abstract

This project report details the prediction of submerged arc welding using design of experiment and regression analysis. SUBMERGED ARC WELDING (SAW) produces coalescence of metals by heating them with an arc between a bare metal electrode and the work. The process has been adapted to a wide range of materials and thicknesses. Various multiple arc configurations may be used to control the weld profile and increase the deposition rates over single arc operation. High weld quality, high deposition rates, dcep penetration, and adaptability to automatic operation make the process suitable for fabrication of large weldments. It is used extensively in pressure vessel fabrication, ship and barge building, railroad car fabrication, pipe manufacturing, and the fabrication of structural members where long welds are required. Automatic SAW installations manufacture mass produced assemblies joined with repetitive short welds. The process is used to weld materials ranging from 0.06 in. (1.5 mm) sheet to thick, heavy weldments. Submerged arc welding is not suitable for all metals and alloys. It is widely used on carbon steels, low alloy structural steels, and stainless steels. It joins some high-strength structural steels, high-carbon steels, and nickel alloys. However, better joint properties are obtained with these metals by using a process with lower heat input to the base metal, such as gas metal arc welding. Design of experiments (DOE) or experimental design is the design of any information-gathering exercises where variation is present, whether under the full control of the experimenter or not. Formal planned experimentation is often used in evaluating physical objects, chemical formulations, structures, components, and materials. Other types of study, and their design, are discussed in the articles on opinion polls and statistical surveys (which are types of observational study), natural experiments and quasi-experiments (for example, quasi-experimental design). In the design of experiments, the experimenter is often interested in the effect of some process or intervention (the "treatment") on some objects (the "experimental units"), which may be people, parts of people, groups of people, plants, animals, etc. Design of experiments is thus a discipline that has very broad application across all the natural and social sciences and engineering. Five levels of the four process parameters i.e. arc voltage, welding current, welding speed and electrode stick out for submerged arc welding (SAW) were considered. An orthogonal array was prepared. Using software XLSTAT 2012, linear and non- linear regression mathematical modelling were done and equations for width, Reinforcement and penetrations were prepared. These equations were dependent on arc voltage; welding current, welding speed and electrode stick out. For different samples and observations, values of voltage, current, welding speed and electrode stick out were put in the equations of width, reinforcement and penetration and their values (width, reinforcement, penetration) were predicted. Regression modelling is good tool for predicting parameters of submerged Arc Welding (SAW).