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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(H_2SO_4+Na_2SO_4)溶液中的腐蚀规律,以及pH值和C1~-对其腐蚀行为的影响。研究表明,300M和Cr9钢的腐蚀电位E_(corr)随pH值增大呈升高趋势,电荷转移电阻R_(ct)减小,腐蚀电流密度I_(corr)增大。溶液pH值的降低能加速300M和Cr9钢的腐蚀。在无Cl~-的(H_2SO_4+Na_2SO_4)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。
The corrosion mechanism of 300M and a new type of ultrahigh strength martensitic steel (Cr9 steel) in (H_2SO_4 + Na_2SO_4) solution was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy and metallographic microscopy. Impact on its corrosion behavior. The results show that the corrosion potential E corr of 300M and Cr9 steels increase with increasing pH, the charge transfer resistance R ct decreases, and the corrosion current density I corr increases. The decrease of solution pH can accelerate the corrosion of 300M and Cr9 steel. In H 2 SO 4 + Na 2 SO 4 solution without Cl ~, the uniform corrosion occurred in 300M and that in Cr 9 steel was pitting corrosion. Cl ~ - promoted the pitting corrosion and changed the anode reaction of Cr 9 steel from passivation to activation Dissolved. Cr9 steel Cr, Mo and Ni content increased its corrosion resistance in acidic medium, the corrosion rate was significantly lower than the 300M steel.