Microstructures and Corrosion Property of AISI 304L Austenitic Stainless Steel Irradiated by High-Current Pulsed Electron Beam

High-current pulsed electron beam (HCPEB) with different pulses was utilized to irradiate AISI 304L stainless steel.The surface microstructures of the irradiated samples were characterized in detail.In particular, the corrosion behaviors of the stainless steel surface with and without HCPEB treatment were evaluated.The experimental results show that the corrosion resistance of the stainless steel after HCPEB treatment is remarkably improved compared with the original sample.Beside the surface purification effect of eliminating impurities due to the crater eruption, the formation of dense surface passive layer, which effectively inhibits the pitting events, is also an important mechanism for the improvement of corrosion resistance of the irradiated materials.Transmission electron microscopy (TEM) observations suggest that a large amount of supersaturated vacancy defects combined with abundant line and planar defects are introduced when the material surface is subjected to the HCPEB irradiation.Furthermore, the agglomerations of the vacancy defects result in the formation of the vacancy cluster defects, such as vacancy dislocation loops and stacking fault tetrahedra (SFTs).Those structural defects in the irradiated surface layer promote the formation of a thick and dense surface passive layer.It prevents corrosive anionic species from passing through the surface oxidation layer and delays the corrosion process, resulting in the improvement of corrosion performance of the irradiated materials.