Study On The Corrosion Detection Technology Of 304 Stainless Steel Based On Electrochemical Noise

Due to good corrosion resistance and mechanical properties, 304 stainless steel is widely used in nuclear power plants. So it is very important to study the corrosion theory of 304 stainless steel for prevention material failure of nuclear power plants.Electrochemical noise is random fluctuations of current and voltage in corrosion system without any additional incentive, which can accurately reflect the corrosion state of material. Based on the actual condition in nuclear power plant, we independently developed electrochemical noise instruments based on ARM9, including the grading amplification for current noise, high precision acquisition by 24-Bit AD, waveform real-time display on computer, data real-time storage by U disk and wireless transmission and so on, which can meet the demand of nuclear power plant basically.Based on Matlab-GUI, electrochemical noise data processing software was completed, which nearly includes all electrochemica l noise data processing methods, such as the statistical of electrochemical parametric, the shot noise analysis method, wavelet analysis method, time-frequency analysis method and so on. The software can process several files simultaneously, which can save time greatly.Corrosion of 304 stainless steel was studied at different temperatures in NaCl solution. The statistical methods, shot noise theory and wavelet analysis method were used for data processing. I found that the corrosion rate increases with temperature. When the temperature rises to a certain extent, the corrosion rate increased significantly and corrosion type transformed from the passivision to pitting. Finally the data analysis results were verified by the corrosion morphology of sample.Corrosion of 304 stainless steel at high temperature was studied in laboratory and nuclear power plant. By analysis for laboratory data, it is found that the standard deviation of current can predict the corrosion rate better under high temperature condition. The analysis result for nuclear power plant data is consistent with the above conclusion fundamentally.