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从孔蚀与缝隙腐蚀两方面考察氮对25-6Mo3型双相不锈钢耐蚀性能的影响。结果表明:随含氮量增加,材料的孔蚀阻力增大,缝隙腐蚀速率下降,且存在关系式:CCT(℃)=17.3+78.4N％(wt)。含氮量越高,氮在钝化膜中的富集程度越大,对于含0.28％N的钢,其最高富集系数可达14;随含氮量增高,孔蚀位置从Y相转移到α相,含0.096％N是孔蚀位置发生转移的分界点。模拟闭塞区试验表明,含氮量越高,闭塞溶液的最终pH值越大,用Nessler特性试剂检验,发现0.28％N钢的闭塞液中存在着NH,从而证实了双相钢中同样存在着氮元素的缓蚀效应。可见氮元素的作用是通过膜内富集,改善γ相耐蚀性能以及与H~+结合形成NH_4~+从而抑制闭塞液酸度变化达到缓蚀效应而得以实现的。
Effect of Nitrogen on Corrosion Resistance of 25-6Mo3 Duplex Stainless Steel from Pitting and Crevice Corrosion. The results show that with the increase of nitrogen content, the corrosion resistance of the material increases and the crevice corrosion rate decreases. The relationship is as follows: CCT (℃) = 17.3 + 78.4N% (wt). The higher the nitrogen content, the greater the enrichment of nitrogen in the passivation film. For the steel containing 0.28% N, the maximum enrichment coefficient can reach 14. With the increase of nitrogen content, the pitting position shifts from Y phase to The alpha phase, containing 0.096% N, is the demarcation point at which pitting occurs. Simulated occlusion zone tests showed that the higher the nitrogen content, the greater the final pH of the occlusion solution. The Nessler characteristic reagent test showed that there was NH in the occlusion fluid of 0.28% N steel, confirming the existence of the same in dual phase steels Corrosion inhibition effect of nitrogen element. It can be seen that the effect of nitrogen element can be achieved through enrichment within the membrane, improvement of corrosion resistance of γ phase and formation of NH_4 ~ + with H ~ + to inhibit the acidity change of the blocking solution to achieve the corrosion inhibition effect.