Metal welding - Fig. 7-420 the macro morphology and corrosion steps of solid core welding sample after pickling in Thailand Dalat. Welding parameters (submerged arc welding, welding current 550A, welding voltage 30V, welding speed 450mm / min, welding line energy 22kj / cm)
Among them, there are reddish brown corrosion product spots distributed on the substrate of 2-month rust layer sample, and the spots are evenly distributed on the whole substrate sample, with little difference between the sunny surface and the back sunny 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. The results show that the color of rust layer is deeper and the distribution of corrosion products is more compact, which indicates that the protection of rust layer is enhanced. After removing the corrosion products, the color of the welded joint surface is light, and with the increase of corrosion cycle, the color of the weld area is deeper than that of the base metal area, which indicates that there is uneven corrosion on the welded joint surface, and it is gradually obvious with the increase of corrosion cycle, but the color difference of the overall corrosion morphology is not large. One year later, there are 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, r = 20.47 μ m. But r is less than 30 μ m. It indicates that the welded joint sample is qualified. After 2 years, there are also corrosion steps in the sample, and the step height in the weld area is lower, r = 20.56 μ m. But r is less than 30 μ m. It indicates that the welded joint sample is qualified.
