Optimization of the welding parameters of steels used in wind towers

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Recent advances in steelmaking technology have remarkably improved the mechanical properties of ferrous alloys and given rise to new classes of steels, for example, high-strength low-alloy (HSLA) steels that are widely used today in shipbuilding, pipelines, nuclear plants, pressure vessels, wind turbine towers, etc. Hitachi Canadian Industries Ltd, Saskatoon, makes extensive use of the automated submerged arc welding (SAW) process for fabrication of pressure vessels, turbine casings, wind turbine towers and other advanced engineering components from HSLA steels. The SAW process is characterized by high heat inputs that give rise to a complex region of microstructural and compositional inhomogeneity called the heat-affected zone (HAZ), the size of which is affected by several welding parameters. One major problem engineers face in the welding industry is selecting appropriate and optimum combinations of input process-control variables in order to achieve the desired weld bead quality and the required structural integrity. Improper selection of welding parameters results in welding defects which cause high economic losses. Selecting appropriate values of process variables is therefore essential in order to control heat-affected zone (HAZ) dimensions, obtain the required bead size and quality, and ensure a predictable and reproducible weld bead, which is critical for obtaining high quality welded products. There is continued need in the manufacturing industry to increase productivity, reduce production cost and improve reliability of welded products. The long-term objective of this study is to increase submerged arc welding efficiency, productivity and cost effectiveness by optimizing the welding parameters. The success of this research project will not only lead to the improvement of the existing knowledge of submerged arc welding process but also increase the profitability of Hitachi Canadian Industries and other Canadian companies utilizing the SAW process. It will also have positive impact on the global competitiveness of Canada in welding technology products.