表面纳米化低碳钢电化学行为尺寸效应

利用超声喷丸技术制备了表面纳米化低碳钢。结构分析表明，最表层低碳钢的晶粒尺度在20nm左右，随着向基体方向靠近，纳米层晶粒尺度逐渐增加，对纳米低碳钢在0．05mol/L H2SO4 0.05mol/L Ns2SO4腐蚀介质中腐蚀速度测试结果表明，纳米化后低碳钢的腐蚀增加；纳米低碳钢的电化学腐蚀行为在尺寸效应，在晶粒尺度小于35nm时，纳米低碳钢的电化学腐蚀速度随晶粒尺寸的增加而降低，当晶粒尺度高于35mm后，晶粒尺寸对腐蚀速度影响不大、纳米化后低碳钢的阳极反应历程不变，阳极交换电流密度提高；而阴极反应历程改变，析氢应容易，并由电化学步骤控制转变为由扩散步骤控制、纳米化后低碳钢阴阳极反应同时得到促进，腐蚀速度增加。

GRAIN- SIZE EFFECT ON THE ELECTROCHEMICAL CORROSION OF SURFACE NANOCRYSTALLIZED LOW CARBON STEEL

A nanocrystallized surface was fabricated on low carbon steel by using ultrasonic shot peening (USSP) technique.The grain size on the top layer of surface nanocrystallized (SNC) low carbon steel was about 20 nm,which increased with the distance from the peening surface.The electrochemical corrosion behaviors of SNC low carbon steels with different grain sizes were studied by electrochemical methods in 0.05 mol/L H 2SO 4 0.05 mol/L Na 2SO 4 aqueous solution.There existed a grain size effect on the electrochemical corrosion of SNC low carbon steel when the grain size was lower than 35 nm.The corrosion rates of SNC low carbon steels increased with the decrease of the grain size.The rise of corrosion rate was attributed to the more active atoms on the grain boundary caused by SNC.