利用高温高压CO2腐蚀模拟试验、微观形貌观察和电化学测试研究了16Mn钢腐蚀行为随时间的变化,探讨腐蚀产物膜形成过程。随腐蚀时间延长,16Mn钢均匀腐蚀速率减小,腐蚀产物晶粒逐渐长大并堆垛紧密,逐渐成膜覆盖于金属表面,膜厚先增加后逐渐趋于稳定,对基体保护能力增强。随腐蚀时间延长,有膜覆盖的16Mn腐蚀电流密度减小,极化电阻增加。腐蚀初期的电化学阻抗谱呈现3个时间常数,随时间延长,中低频区感抗弧逐渐消失,完整的腐蚀产物膜覆盖金属表面而对电化学反应过程产生影响。
High temperature high pressure corrosion tests, microstructure observation and electrochemical tests were used to analyze the effects of corrosion time on the CO2 corrosion of 16Mn steel and the formation process of the corrosion scale. With extending corrosion time, CO2 corrosion rate of 16Mn steel decreased. Grains of corrosion product grew to form a scale layer, which became more and more compact during corrosion. The corrosion current density ico. reduced and polarization resistance Rp decreased at the same time. The electrochemical impedance spectroscopy characters have three time-loops in the beginning, but the inductive arc disappeared at the end because of coverage of the corrosion scale and its protection.