The Application And Research Of Time-Frequency Analysis Technology In Stress Corrosion Cracking Of Metal

In our daily life and production, the metal corrosion brings us great economic loss and social harm. For the"catastrophic corrosion"—SCC, the metal can break when there is no plastic deformation of the macro, so it's unpredictable. Therefore, the performance measurement and characterization study of SCC has great significance for the development of high-intensity and ultra-high strength steel. When the device has the trend of SCC in the corrosion medium, it becomes very important to predict and prevent the corrosion by electrochemical method.During the measurement progress of the electrochemical noise(ECN), there's no need to add external disturbance, which may change the electrodes reaction generates on electrodes surface. So, the ECN technology can reflect the real corrosion situation. Also its measurement method is simple and the equipments don't ask for much. With the computer's great development in data acquisiting, signal processing and express analysis technique, the ECN technology has been widely used in the area of metal corrosion.The article's main task :1. For the non-stationary signal, ECN signal generated during SCC, analyses the limitations of the traditional analysis method, such as Fourier transform, maximum entropy method and so on.2. Analyses the advantages of wavelet transform in the ECN of SCC and removes the measurement interference in the signal with wavelet threshold denoising.3. Combines the energy distribution method with wavelet transform to process the ECN signal of SCC. Determines the main energy bands and reconstructs the signal, extracts the electrochemical characters and analyses the SCC progress.4. Through the slow strain rate testing, processes the ECN signal generates during the SCC progress of 40Cr steel. It shows that using wavelet threshold denoising singly may distort the signal part that reflects the electrochemical characters of SCC. With the EDP method based on wavelet transform, the electrochemical characters of SCC can be extracted better when the interference is inhibited at the same time.