中文摘要：

采用动电位极化、电化学阻抗和金相显微技术研究了300M和一种新型超高强度马氏体钢（简称Cr9钢）在（H2S04＋Na23O4）溶液中的腐蚀规律，以及pH值和Cl^-对其腐蚀行为的影响。研究表明，300M和Cr9钢的腐蚀电位上Ecorr随pH值增大呈升高趋势，电荷转移电阻Rct减小，腐蚀电流密度Lcorr增大。溶液pH值的降低能加速300M和Cr9钢的腐蚀。在无Cr的（H2SO4＋Na2SO4）溶液中，300M发生均匀腐蚀，而Cr9钢则表现为点蚀；Cl^-能促进点蚀的发生，使Cr9钢的阳极反应由钝化转变为活化溶解。Cr9钢中Cr、Mo和Ni元素含量的增加能提高其在酸性介质中的耐蚀性，腐蚀速率明显低于300M钢。

英文摘要：

The electrochemical behavior of 300M and a new kind of ultra high strength steel （Cr9 for short） in sulfate acidic environment, as well as the effects of pH and C1- concentration on the corrosion behavior were studied by potentiodynamic polarization curve, EIS, and metallographic microscope. The results showed that with increasing pH value, the corrosion potentials Ecorr of 300M and Cr9 shifted towards the positive direction, the charge-transfer resistances Rct increased, and the corrosion current densities icorr decreased. The （H2SO4＋Na2SO4） solution with decreasing pH value suppressed the corrosion rates of 300M and Cr9. In the chloride-free sulfate acidic solution, general corrosion on the 300M surface occurred, while on Cr9 surface pitting occurred. The addition of chloride ions induced the pittings and transformed the passivity of Cr9 into an active dissolution state. Cr9 steel contains more contents of Cr, Mo and Ni, and the elements enhanced the corrosion resistance in acidic solution and made a much lower corrosion rate compared with 300M.