Numerical and thermal analysis of mechanical properties degradations and distortions in steel weld joint

Abstract

To quantify the degradation of mechanical properties and material distortion associated with steel weld. Twin mild steel plates each of dimension 20 mm × 100 mm × 6 mm were joined in butt configuration using the arc welding method. Thermal and mechanical analyses of the system were carried out using a numerical method and the associated heat transfer/stress distribution problems were formulated based on FEM. The thermal analysis involves numerical evaluation of the transient temperature distribution in the specimen. The effects of some operational parameters including welding speed and welding power on the temperature profile were studied independently. The results suggest that a good combination of these operational variables guarantees stable welding operation which in turn assists in achieving a quality welded joint. The numerical results were validated using experimental data and further applied to solve the prevailing mechanical problem. The maximum residual stress of 200 N/mm2 was recorded along the weld line while a maximum distortion of 15 mm was recorded numerically at the free end of the steel segment at the prevailing stress condition. Therefore it is recommended that maintaining low but sufficient high welding power helps to minimize excessive temperature rise in the base metal and improves stress distribution along the welding line, which in turn mitigates degradation of tensile strength and other mechanical properties.