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在不改变耐海水腐蚀球墨铸铁基本元素C,Si,Mn,Cu和Al含量前提下,设计了不同Cr和Ni含量的合金系,采用金相观察、硬度测试、失重法测试、EPMA面扫描分析和极化曲线分析等手段研究了其切削性能和耐海水腐蚀的影响规律,获得了一种耐海水腐蚀球墨铸铁的优化成分。结果表明:Cr,Cu和Si等在材料表面形成一层薄且紧密附着的钝化膜,有利于提高合金铸铁的耐蚀性;Ni可以提高腐蚀过程中基体的电极电位,明显降低球墨铸铁腐蚀电流密度,降低腐蚀速率;当Cr含量为0.6%~0.8%(质量分数)时,既可以保证切削性能,又能提高耐蚀性。与普通的球墨铸铁相比,成分优化设计的球墨铸铁的耐蚀性明显提高。
Under the premise of not changing the contents of C, Si, Mn, Cu and Al, the basic elements of seawater corrosion resistant ductile iron, the alloy systems with different contents of Cr and Ni were designed. Metallographic observation, hardness test, weight loss test, EPMA surface scanning analysis And polarization curve analysis methods to study the cutting performance and seawater corrosion resistance of the law to obtain a seawater corrosion resistant nodular cast iron optimization components. The results showed that Cr, Cu and Si formed a thin and closely adhered passivation film on the surface of the material, which was beneficial to improve the corrosion resistance of the alloy cast iron. Ni could improve the electrode potential of the substrate during the corrosion and significantly reduce the ductile iron corrosion Current density, reduce the corrosion rate; when the Cr content of 0.6% to 0.8% (mass fraction), both to ensure cutting performance, but also improve corrosion resistance. Compared with ordinary ductile iron, the composition of the optimal design of ductile iron corrosion resistance improved significantly.