Evaluation of high strength TMCP steel weld for use in cold regions

An experimental program which includes the observation of microstructures and the Charpy impact test was conducted to evaluate the applicability of high strength TMCP steel (SM570-TMC) weld to cold regions. The experiments were also carried out on conventional structural steel (SM490B) weld for comparison. Standard V-notch Charpy specimens were prepared and tested under dynamic loading condition. The service temperatures of the weld metal, the HAZ (heat affected zone) and the base metal were derived and their applicability to cold regions was assessed by the absorbed energy, the impact test requirement and the microstructure. Test results revealed that the base metal of the SM570-TMC weld has much higher impact toughness at low temperatures compared to that of the SM490B weld, while the HAZ and the weld metal exhibit much lower impact toughness than the base metal and have a service temperature similar to their counterparts in the SM490B weld. These results imply that for the application of the TMCP steel weld to cold regions, adoption of appropriate welding process which guarantees the low temperature impact toughness of the HAZ and the weld metal along with suitable electrode should be made, at which the future works are aimed.

► The applicability of high strength TMCP steel weld to cold regions was evaluated.
► The assessment was based on the Charpy impact test and metallographic observation.
► Impact toughness of the HAZ and weld metal is determined by the welding process.
► Adoption of appropriate welding process and suitable electrode should be made.