空蚀对20SiMn在3%NaCl溶液中的电化学腐蚀行为的影响

利用带电化学测试系统的磁致伸缩空蚀试验机研究了20SiMn低合金钢在3%NaCl水溶液中的电化学腐蚀行为，通过空蚀和静态条件下的自腐蚀电位变化以及交流阻抗谱和动电位极化曲线的比较，分析了空蚀加速20SiMn低合金钢电化学腐蚀的机理.结果表明，空蚀使20SiMn低合金钢的自腐蚀电位正移200 mV，并显著降低电荷转移电阻和线性极化电阻，使电化学腐蚀速率增大约54倍；随着空蚀的进行，电荷转移电阻和线性极化电阻减小，空蚀3 h后逐渐趋于稳定.

EFFECT OF CAVITATION ON ELECTROCHEMICAL CORROSION BEHAVIOR OF 20SiMn LOW ALLOY STEEL IN 3%NaCl SOLUTION

The effect of cavitation on electrochemical corrosion behavior of 20SiMn low alloy steel in 3%NaCl solution was investigated by using a magnetostriction-induced cavitation erosion facility with electrochemical testing system.The synergistic action of corosion and cavitation was characterized by measuring free corrosion potential,potentiodynamic polarization curves,electrochemical impedance spectra.The morphology of damaged surfaces was observed by scanning electron microscope(SEM).The results showed that cavitation strongly affected the electrochemical behavior of 20SiMn low alloy steel.Cavitation shifted the free corrosion potential towards positive by 200 mV and reduced both the charge transfer resistance and linear polarization resistance.The magnitude of impedance and linear polarization resistance decreased in the early stage of cavitation and then level off after cavitation 3h.The electrochemical corrosion rate in presence of cavitation was 53 times higher than that in absence of cavitation.