Experimental Study On Corrosion Rate And Mechanical Properties Of Carbon Steel In Chloride Environment

Developing a blue economy and building a maritime power is one of ways to achieve the great rejuvenation of the Chinese nation.China is a maritime power with 18,000 kilometers of continental coastline.Carbon steel,as one of the most commonly steels,is the most widely used building material in the construction of China's maritime power and plays a vital role in infrastructure construction.Due to the extremely severe corrosive environment of the ocean,marine corrosion has caused huge economic losses and safety accidents to the society.Therefore,research on the change rate of the corrosion rate and mechanical properties of carbon steel in the chloride salt environment has been conducted to ensure that the structure can be long-term in the marine environment Safe use is of great significance.This paper was supported by the National Grain Public Welfare Research Project(201413007-01),based on a research method combining theoretical analysis,experimental research and numerical analysis,this article carried out a research on the corrosion of carbon steel in different chloride salt concentration environments.The corrosion rate of carbon steel was studied by weight loss test and electrochemical test.The mechanical properties of carbon steel were studied by tensile test,bending test and numerical analysis.The main research content is as follows::1.The corrosion rate of carbon steel in different chloride concentrations was studied.The corrosion law of carbon steel in different chloride concentration environment was studied by weight loss test,and the change law of corrosion morphology and corrosion rate of carbon steel in different chloride concentration environment was obtained.The corrosion resistance of carbon steel was evaluated according to the corrosion law.The corrosion rate prediction model of carbon steel in different chloride concentration environment was established by theoretical analysis.2.The validity of the electrochemical test was verified by comparing with the results of weight-loss test.The corrosion rate of carbon steel in different chloride concentrations was studied by electrochemical experiments.It was found that the surface rust layer of carbon steel would affect the electrochemical test results.The ?-FeOOH in black inner rust layer occurred reduction reaction under polarization current,which would affect the measured corrosion current density,resulting in deviation between the electrochemical test and weight-loss test.The deviation would increase with the increase of corrosion time.Before the electrochemical test,the electrode was pre-polarized by constant current,which can effectively reduce the error caused by rust layer,and the improved corrosion rate was consistent with the weight loss method.3.The mechanical properties of corroded carbon steel were studied.The thickness loss rate of the weakest section of the carbon steel specimen was used as the standard to evaluate the corrosion degree.The mechanical properties of corroded carbon steel were obtained by tensile test.The law of degradation of material properties such as tensile strength,yield strength and elongation after fracture was established.Bending test was carried out on the corrosion specimens,and the bending resistance of the specimens was evaluated.The bending resistance grade of carbon steel specimens with different corrosion cycles belonged to A1 grade.4.The mechanical properties of carbon steels with different corrosion periods were numerically analyzed.Used large finite element analysis software,the mechanical properties of carbon steel models with different corrosion periods were numerically analyzed.The validity of the model was verified by statistical analysis of the data of yield load and ultimate tensile load,which was consistent with the change of test results.