MODELLING OF SAW PARAMETERS AND ITS MECHANICAL PROPERTIES FOR JOINING STRUCTURAL STEELS

Abstract

Ethiopia nearly 85 per cent of people is morality depends on agriculture; the government of Ethiopia emphasis on Farm Mechanization for bringing the improvement in crop production using modern equipment and tools. However, the Modern equipment development needs improved machineries for fabrication. Moreover, the metal joining technology; like Submerged Arc Welding (SAW) available is very advance and made welding of thicker plats and welded structures. Therefore, while using this modern technology for metals; like mild steel, stainless steel etc; the present study is conducted; to predict the weld geometry, mechanical properties and HAZ dimensions of welded joint by using automatic submerged arc welding. The mathematical models were developed by using the statistical methods, like Regression analysis. The important process control variables of welding; like voltage, current and travel speed were regressed with bead characteristics; like quality, penetration, reinforcement, bead width etc; and the mechanical properties; such as bead hardness, HAZ hardness etc. Nevertheless; these mathematical equations between the weld bead characteristics and mechanical properties with the welding parameters will be very useful during actual fabrication work. Moreover; the dimensions and shape of the weld bead largely determine the strength of welded joint. However, for using automatic Submerged Arc Welding effectively, it is essential to develop equations that express mathematically the weld bead parameters in terms of process variables, the variation in HAZ dimensions and microstructure. The relationship between welding variables and weld feature; like hardness, bead geometry and HAZ width also reduces the cost of weld procedure development by decreasing the number of trial runs. In order to ensure adequate weld bead quality; it is necessary that various welding variables should be in proper balance. Therefore, it is essential to know the effect of the process variables individually and in combination on the resulting weld bead dimensions. These dimensions not only control the type of microstructure but also determine the stress carrying capacity of a welded joint. The developed mathematical models in which the data is represented can be programmed, fed to a computer and used to develop an expert welding system. Statistical Analysis Software’s like SPSS and MS Excel were used for the complete analysis.