Investigation of thermal distortion effects in gas metal arc welding of low carbon steel sheets

In this study, thermomechanical analysis of low carbon sheet steels under weld heat input were investigated by experiments and numerical simulations. The weld heat input variation at plates were provided by Gas Tungsten Ark (GTA) welding process controlling welding speed and current. Thermal deflection results were determined by three dimensional coordinate measuring device. The numerical analysis was carried out using the finite element program Ansys with three dimensional model containing thermal and mechanical analysis parts. The weld heat input effects in experiments were investigated using the gauss heat flux approach in numerical analysis. The change of mechanical properties of sheet metal under heat input was investigated by tensile tests, microhardness and microstructure measurements. In the tensile specimens the fracture was occurred from the base metal. The tensile strength and ductility was decreased depending on the weld amperage and weld speed. The microhardness values of welded and heat affected zones were higher than the base metal. The grain growth was observed at the SEM (Scanning Electron Microscope) measurements of Heat affected zone for lower welding speeds. The good agreement was observed between the numerical analysis and experimental deflection results. In the numerical analysis, the tensile residual stresses are determined at the yield limit at the welding zone.