Study on surface characteristics and stochastic model of corroded steel in neutral salt spray environment

Abstract

To study the surface morphology characteristic of corroded steel in a neutral salt spray environment, an artificial accelerated corrosion tests were carried out and eight batches of specimens with different corrosion ages were obtained. The corroded steel surface morphologies were collected by a non-contact 3D profiler, and the characteristic parameters were extracted by a special analysis program. The results showed that the corrosion depth of steel surfaces generally follows a normal distribution, while the pit depth and aspect ratio follow a lognormal distribution. As the degree of corrosion increases, the average value and standard deviation of corrosion depth, and logarithm mean value of the pit depth increase, while the logarithm mean value of the pit aspect ratio decreases. In addition, the pit density fluctuates in the range of 20–30 and the conical pits on the steel surface account for the largest proportion in the neutral salt spray corrosion environment. Based on the statistical results and parameter change laws, the stochastic field model of corrosion depth and the random distribution model of corrosion pit were established, and the corroded surfaces were reconstructed in the neutral salt spray corrosion environment.