Effect of pre-corrosion of NaCl solution on surface cavitation erosion of 304 stainless steel

To explore the effect of corrosion on cavitation erosion, the experiment was performed on corrosion and cavitation erosion of 304 stainless steel samples. Different concentrations of sodium chloride solution were adopted for corrosion. The experiments of cavitation erosion were conducted based on the waterjet cavitation test bench conforming to ASTM G134—95 of standard test method for erosion of solid materials by a cavitating liquid jet. The cavitation erosion characteristics of the 304 austenitic stainless steel samples were comprehensively analyzed according to cumulative mass loss, surface morphology and surface roughness. The analysis results show that the corrosion degree of 304 stainless steel is weakened first with latter strengthening by increasing the concentration of NaCl solution. The corrosion of NaCl solution contributes to the delay of cavitation erosion in a certain concentration, and the delaying effect is enhanced first with latter mitigating with the increasing of NaCl solution concentration. The minimum cavitation erosion is obtained at the concentration of NaCl solution of 3.5%. For the same corrosion time and cavitation erosion time, the plastic deformation is strengthened, and the thickness of twin layer of tested samples is gradually increased with the increasing of NaCl solution concentration, while the cumulative mass loss and the surface roughness are decreased first with latter increasing during the process. Compared to the sample undergoing cavitation erosion, the sample suffering from corrosion and cavitation erosion is featured by relatively slight cavitation erosion and smooth surface. Due to the cavitation erosion, the grains are preferentially oriented and refined.