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采用动电位极化、循环极化、电化学阻抗谱、Mott-Schottky曲线结合表面形貌观察,研究了利用等通道转角挤压方法制备的晶粒尺寸为(130±30)nm的超细晶304L不锈钢在含Cl-溶液(0.05 mol/L H2SO4+0.05 mol/L Na Cl)中的点蚀行为.研究表明,超细晶材料比粗晶材料具有更高的腐蚀电流密度和钝化电流密度,更低的腐蚀电位、破钝电位和保护电位,且钝化区更窄.严重塑性变形引起304L不锈钢材料晶粒显著细化,一方面增加了表面钝化膜的施主密度和扩散系数,降低了钝化膜的致密性,使Cl-在材料表面的吸附能力增强;另一方面增加了晶界含量,使Cl-沿晶界向内扩散能力增强,促进了点蚀形核和长大.
By using potentiodynamic polarization, cyclic polarization, electrochemical impedance spectroscopy and Mott-Schottky curve in combination with surface morphology observation, the ultrafine grain with the size of (130 ± 30) nm Pitting corrosion behavior of 304L stainless steel in Cl-containing solution (0.05 mol / L H2SO4 + 0.05 mol / L NaCl) was studied. The results show that the ultrafine-grained material has higher corrosion current density and passivation current density , Lower corrosion potential, broken blunder potential and protective potential, and the passivation zone is narrower.Several plastic deformation causes the 304L stainless steel grain refinement significantly, on the one hand increases the donor density and diffusion coefficient of the surface passivation film, reducing The densification of the passivation film enhances the adsorption capacity of Cl- on the surface of the material. On the other hand, it increases the content of the grain boundary and enhances the inward diffusion of Cl- along the grain boundaries, which promotes the nucleation and growth of pitting corrosion.