Microstructure and mechanical properties of welded joints of high-strength steel S460J4W with improved atmospheric corrosion resistance for bridgebuilding

The microstructure and mechanical properties of 50-mm thick-walled welded joints made of S460J4W microalloyed high-strength С-Mn-Si-Cr-Cu-Nb-V-Ti steel with atmospheric corrosion resistance were under investigation. The study examines joints, welded by automatic arc welding (SAW 121-2) with a heating input of 3.1±0.1 kJ and V-shaped symmetrical edge preparation, as well as by semi-automatic arc welding with a heat input of 1.5±0.1 kJ and ½V-shaped asymmetrical edge preparation. The microstructural features of the critical heat-affected zones (HAZ) were identified and described together with microhardness and impact toughness investigations. Extra strain aged and weldability tests were performed in accordance with the requirements of EN 10225-1:2019, including the Controlled Thermal Severity (CTS) test and the Bend-on-Plate test).