Surface topography and stress concentration analysis for corroded high strength steel plate

In this paper, salt spray tests were firstly conducted for Q690 high strength steel plates. After the corrosion tests, the corrosion products were removed and the weight loss ratio was obtained. Then the topographies of the rough surfaces were scanned by a 3D surface profiler, and the 3D coordinates of the corroded surfaces were exported. Based on the data, the topographic feature parameters were determined, the uniform corrosion depth was calculated, and the extreme value analysis was conducted for the pitting corrosion depth to investigate its stochastic features. Finally, the corroded surfaces were restored and the finite element models of the scanned segments were established, which were validated by the experimental results and used to conduct the stress concentration analysis. The experimental results showed that the topographic feature parameters were linearly related to the weight loss ratio, and the maximum pitting depth conformed to the Frechat distribution. By conducting finite element analysis, it was concluded that under the uniaxial tensile load, the corroded steel plate showed an obvious stress concentration effect and most nodes were in a multiaxial stress state. In terms of the characteristic loads, both uniform and pitting corrosion induced the yield load and the ultimate load degradation. Regarding the uniform corrosion component, the loss percentage of the characteristic load was equal to the corresponding weight loss ratio. However, the loss percentages of the characteristic loads caused by pitting corrosion were smaller than the pitting weight loss ratio due to the stress concentration.