Objective To study the effect of Si on the resistance of low alloy steel to sea water corrosion by electrochemical methods. Methods Low alloy steels with different mass fractions of Si were smelted by vacuum arc furnace. The corrosion resistance of the steel in sea water was evaluated by polarization tests. The corrosion resistance of the rust layer after full immersion was studied by linear polarization test and EIS test. The composition of inclusions was studied by scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX). Results The experiment results indicated that when the Si content was less than 0.9%, the uniform corrosion rate increased with the increase of Si content;when the Si content was more than 0.9%, the corrosion rate decreased with increasing content of Si;the corrosion resistance of the steel decreased as the time of immersion prolonged. Conclusion When the Si content was 0.9%, the steel had the best corrosion resistance;the protection ability of rust layer was limited.%目的：研究Si对低合金钢耐海水腐蚀性能的影响。方法采用真空电弧炉冶炼了不同硅含量的低合金钢，通过极化试验研究钢在海水中的腐蚀特性。采用交流阻抗和线性极化研究锈层对钢的保护作用，并对夹杂物进行SEM及EDAX分析。结果当硅的质量分数小于0.9%时，其在海水中的腐蚀速度随硅的质量分数增加而增加；当硅的质量分数大于0.9%时，其在海水中的腐蚀速度随硅含量的增加而减小。随浸泡时间延长，钢的耐蚀性降低。结论 Si的质量分数为0.9%时，钢耐蚀性的最好，锈层对钢的腐蚀不具有保护作用。
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