Metal welding - Fig. 3-3Ni welding sample 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).
Among them, there are gray corrosion products distributed on the base of 2-month rust layer sample, which are more uniform, few reddish brown corrosion products, and more reddish brown corrosion products on the back surface. 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. At the same time, the distribution of corrosion products is more intensive, and the corrosion products on the back surface are less. At the same time, there is no obvious difference between the weld zone and the base metal zone after removing the corrosion products, which indicates that there is little difference in corrosion resistance between the weld zone and the base metal zone. For one-year specimens, there are some 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, r = 6.91 μ m. But r is less than 30 μ m. It indicates that the welded joint sample is qualified. For the 2-year sample, the step height of the weld zone is higher than that of the base metal zone, which indicates that the corrosion resistance of the weld metal is better and the welded joint sample is qualified.
