| In recent years,coal chemical industry has developed rapidly Under the policy guidance,coal chemical equipment also increased rapidly.Stainless steel is widely used in coal chemical equipment,but Coal chemical medium containing a large number of chloride ions,This leads to the problem of chloride ion corrosion in the process of using coal chemical equipment.At home and abroad,the study on the corrosion of stainless steel materials in the coal chemical industry is few.So this paper aimed at the corrosion of a coal chemical equipment.The stress corrosion and pitting corrosion behavior of316L and 304 stainless steel in coal chemical ash water medium were studied.The main work is summarized as follows:According to the engineering practice and combined with literature data,the experimental scheme of stress loop is designed.The scheme can simulate the stress corrosion environment of stainless steel materials in coal chemical equipment,and then judge the stress corrosion sensitivity of stainless steel in the research environment.The experimental results show that the stress corrosion cracking of the two kinds of stainless steel will not occur in the studied environment.So pitting is the focus of the next step.In order to study the corrosion behavior of stainless steel in ash water,The passivation potential and pitting potential of 316L and 304 stainless steel in the ash water solution are obtained by dynamic potential scanning curve method.Then,the characteristics of passive film of stainless steel were obtained by electrochemical impedance spectroscopy and M-S curve method.The data provide the basis for the configuration of the simulation solution and the analysis of the influence of various factors on the pitting corrosion behavior of stainless steel.The effects of Cl—,SO42—,pH value and other factors on the pitting corrosion behavior of stainless steel were investigated by means of dynamic potential scanning curve,electrochemical impedance spectroscopy and immersion test on the basis of existing research.Results show:The decrease of chloride concentration,the increase of the concentration of sulfate ions and the pH value of solution can inhibit the pitting corrosion of 304 and316L stainless steel in the scope of the study.The pitting corrosion resistance of two kinds of stainless steel in simulated solution with different chloride ion concentration,different sulfate ion concentration and different pH value was compared by using the obtained data.And the change trends of pitting corrosion data of two kinds of stainless steel were analyzed.This paper provides experimental support for the corrosion protection of304 and 316L stainless steel in the coal chemical industry,it also provides reference for new coal chemical equipment design. |
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