Three seawater resistance steels had been selected. Their pitting susceptibility was compared by means of potentiodynamic polarization tests in 3%(wt.%) NaCl solution. The pitting propagation rate was evaluated by indoor interval hanging plate tests and simulating occluded corrosion cell test in 3%(wt.%) sea salt solution and artificial sea water sea water respectively. The composition of inclusions, corrosive feature and characteristic of rust layer had been studied by microscope, electron probe micro-analyzer (EPMA), scanning electro microscopy (SEM) and X-ray diffraction (XRD). The results indicate that Ni-Cu-P steel exhibits stronger pitting susceptibility than Cr-Cu-P and Cr-Cu-Al steel do, while the pitting susceptibility of Cr-Cu-P is the weakest one. Under the same condition, pit propagation rate of Cr-Cu-P and Cr-Cu-Al steel is close, which is obviously greater than that of Ni-Cu-P steel. The composition of inner rust layer of three steels are Fe3O4,α-FeOOH and amorphous oxides, however, rust layers formed on Cr-Cu-P and Cr-Cu-Al steel are much more compact than Ni-Cu-P steel. In the acidic pits, Cr decreases potential of matrix, and then accelerates pit propagation;while Ni helps to improve potential and therefore tends to decrease the pit propagation rate.%选择了三种典型的耐海水腐蚀钢，在pH为10的3%(wt.%)NaCl溶液中进行了极化试验，比较了钢的点蚀诱发敏感性；在3%(wt.%)海盐水和人造海水中分别进行了间浸挂片试验和模拟闭塞腐蚀电池试验，评价了钢的点蚀扩展速度；利用金相显微镜、电子探针(EPMA)、扫描电镜(SEM)和X射线衍射(XRD)分析了钢中夹杂物、腐蚀形貌和锈层的特征。结果表明，Ni-Cu-P钢的点蚀诱发敏感性比Cr-Cu-Ni钢强，Cr-Cu-P钢最弱。在相同条件下，Cr-Cu-P和Cr-Cu-Ni钢的点蚀扩展速度接近，但都明显大于Ni-Cu-P钢。四种钢的内锈层主要组成均为Fe3O4、α-FeOOH和和少量的非晶化合物，但Cr-Cu-P和Cr-Cu-Ni钢的内锈层明显比Ni-Cu-P钢致密。在酸化的蚀坑内， Cr可降低钢基体的电位，从而促进蚀坑的扩展；而Ni的添加则提高钢基体的电位，从而有助于降低钢的点蚀扩展速度。
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