研究表明，对普通灰铸铁加少量合金元素及变质剂，可使其耐海水腐蚀率提高４ 倍；这是由于在腐蚀过程中，铸铁表面形成了一层复合保护膜．对该膜的形成过程进行了探讨，发现了一些有意义的新现象． The research shows that adding a small amount of alloying elements and modifiers to common gray cast iron can increase the seawater corrosion resistance by 4 times. This is because a layer of composite protective film is formed on the surface of the cast iron during the corrosion process. The membrane formation process was explored and found some interesting new phenomenon.