LAUSR

The corrosion resistance of plates 0.4 mm in thickness made of AISI 316 stainless steel is studied under the conditions of ultrasonic vibration with a frequency of 28 kHz and a power of 50 W applied to the end of the sample. The tests are performed by the methods of potentiodynamic and galvanostatic polarization in 10 g/liter and 35 g/liter NaCl solutions at the standard temperature. According to the results of electrochemical studies, in the presence of ultrasonic vibration, the rate of dissolution of steel becomes 30 times lower as compared with the sample not subjected to vibration. These results are confirmed by the analysis of morphology of the specimen surface after testing in a scanning electron microscope. The mechanism of suppression of pitting by ultrasound is proposed. It can be described as the removal of the layer of corrosion products in the stage of formation of metastable pits with their subsequent repassivation. Ultrasound vibration proves to be a promising method for increasing the corrosion resistance of stainless steels. This method can be used to protect the plates of heat exchangers in the heat-and-water supply systems.