Corrosion Development And Image Characters Of Q235 Steel In Atmospheric Environment

Atmospheric corrosion is the corrosion of metals that occurs under atmospheric environment,which is the most common form of environmental corrosion.The development of modern industry demands more on the corrosion resistance of metal materials,and the development of these materials is closely related to the research on the mechanism of atmospheric corrosion.Therefore,it will be of great significance to explore in-situ analysis for corroded metals and to improve the analytical test to study the atmospheric corrosion process and mechanism.The corrosion behavior of Q235 steel under atmospheric condition has been studied in this paper.Information about the composition of rust layers was obtained through image processing.The correlation between corrosion behavior and image information of Q235 steel under thin electrolyte film was studied through abstracting image characteristic information and compared it with electrochemical information.The results show that atmospheric corrosion of Q235 steel appears around pearlite and presents the character of local corrosion which developed to uniform corrosion afterwards.According to the result of using the wire beam electrode(WBE),the mean corrosion potential and the corrosion potential standard deviation decreased,and the anode area enlarged with increasing time.Analysis of the neural network shows that the content of ?-FeOOH in rust layers increased with time blocked the process of oxygen diffusion,resulting corrosion patterns being transformed from local features to uniform features.In conclusion,electrochemical information shows the trend to uniform feature,and image information show that protective rust formed with time.Corrosion behavior of Q235 steel is correlated with image feature information.Field exposure test and image processing method were used to study the corrosion image evolution of Q235 steel in marine atmosphere.The results show that,at the beginning of the test,uniform rust layer has not been formed on the surface of the sample,and the surface of the metal substrate is covered with rust layer over time,showing the change trend from orange to reddish brown;the color image processing method is used to obtain characters of corrosion images of Q235 Steel exposed to marine atmosphere environment.According to the waveform characteristics of each image 15 characters have been extracted.The neural network training results show that there is a good correlation between the image eigenvalues and weightlessness data.Using the artificial neural network established in the laboratory to synthesize the rust layer images,the trend of the proportion of the protective rust layer in Q235 steel with time is analyzed.Q235 WBE tow electrode were test in normal environment and magnetic field environment.From the corrosion image and WBE test analysis,the anode area is mainly distributed in four weeks and the cathode area in the middle of more set compared with the normal environment.Besides the number of anodes in the Q235 WBE decreased and the corrosion heterogeneity increases in magnetic field environment.In order to have a further study on the mechanism that the magnetic field act on the electrode reaction,the Q235 WBE was tested in the magnetized solution.The results show that the corrosion behavior of Q235 in the magnetized solution is very close to that in the magnetic field.The magnetized solution plays an important role in how the magnetic field acts on corrosion behaviors of carbon steel.