Metal welding - Fig. 1-DH36 welding joint was exposed to the sun, and the macro morphology and corrosion steps after pickling were taken back. Through CO2 gas shielded welding (250A, 29V, 300mm / min, 14.5 kJ / cm).
It can be seen from the figure that there are reddish brown corrosion product spots distributed on the matrix of 2-month rust layer sample, and the spots are evenly distributed on the whole matrix sample. Gray corrosion products were distributed on the substrate of 1-year rust layer samples, and the color of corrosion products was lighter, and the corrosion product spots were evenly distributed on the substrate. Gray black corrosion products were distributed on the substrate of 2-year rust layer samples, and the corrosion products were denser than those in the first two cycles. After removing the corrosion products, there is an obvious boundary between the weld zone and the base metal zone, which indicates that there is a certain difference in corrosion between the weld zone and the base metal zone, and the difference in corrosion morphology is more obvious with the increase of the cycle. There are some corrosion steps between the weld zone and the base metal zone. The corrosion of the base metal zone is lighter than that of the weld zone, and the step height of the weld zone is lower. 1 year R = 15.49 μ m. 2 years R = 9.35 μ m. This phenomenon is related to the sample and measurement error, but the R value is less than 30 μ m. It indicates that DH36 welded joint sample is qualified.
