| Weathering steel, also known as weather resisting steel, has excellent corrosion resistance in atmospheric environment, which is belong to low-alloy high-strength steel. After reducing the carbon content and adding a small amount of alloying elements,a dense rust layer with strong adhesion will form in the surface of weathering steel. This special rust layer can further spread and develop of the corrosion to protect the basic under the rust. So, it can slow down the corrosion rate, thereby enhance the resistance of atmospheric corrosion of steel. This paper carries out the experimental study which researches the fatigue behavior of wreathing steel after corrosion in order to obtain the fatigue performance of wreathing steel, and compared with the welding specimens and ordinary steels specimens, which provides data to support for the use of weathering steel without coating.Firstly, this paper designs and conducts the calibration experiment of acetate salt spray cycle test, and observe the morphology of the specimen after corrosion.Compared with the results of natural atmospheric corrosion, the acceleration of the acetonitrile cycle test is calculated,and the correlation between the acetate salt spray cycle test and natural atmospheric corrosion is analyzed by grey relational analysis.Next, this paper designs and conducts the fatigue experiment of Q355NHD wreathing steel and welding specimen which is corroded, and Q345qD steel. The preparation of the test specimen is described in detail. The results of fatigue experiment and fatigue fracture morphology are introduced. The results show that the fatigue performance of the weathering steel and butt weld specimens is accelerated by the accelerated corrosion experiment, but it still meets the fatigue design requirements of the bridge steel. The S-N curves of the specimens are fitted according to the experimental data, including the Basquin model and the three-parameter model.P-S-N curves are obtained using a maximum likelihood estimate and P-S-N curves with a survival rate of 90% and 95% are calculated, and the y-P-S-N curves are calculated at the specified confidence level.ANSYS nCode Designlife software is used to analyze and calculate the fatigue test results. The calculated fatigue life results are in good agreement with the median S-N curve in high stress levels.Finally, this paper designs and conducts the accelerate corrosion experiment of the weathering steel painting and the carbon steel painting. And observe the macro-morphology of the two painting to compare the protective effect of the painting in the corrosion environment. Through the test, it is found that the weathering steel painting durability is better than the painting on the carbon steel surface. |
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