合金元素含量对316不锈钢耐点蚀性能影响

Influence of alloying elements concentrations on pitting corrosion resistance of AISI 316 stainless steels

点腐蚀是奥氏体不锈钢的常见局部腐蚀形式,会严重影响奥氏体不锈钢的性能和使用。选取4组不同化学成分的316不锈钢板试样,在10%三氯化铁溶液中进行点腐蚀试验。检测了点蚀坑的宏观形貌和腐蚀速率,通过SEM和EDS检测了腐蚀坑微观形貌以及点蚀坑邻近区域的合金元素分布,分析了主要合金元素对316不锈钢耐点蚀当量的影响规律。结果表明:Cr元素对316不锈钢在氯离子介质中的耐点蚀性能有着显著的有利影响,Mo元素含量的增加可以提高316不锈钢的耐点蚀性能,而Mn元素会降低316不锈钢在氯离子介质中的耐点蚀性能。根据试验结果,提出了考虑Mn元素不利影响的修正耐点蚀当量PRE计算公式。

As a common type of local corrosion for stainless steels,pitting corrosion has a harmful effect on the performance and application of austenitic stainless steels.The AISI 316 stainless steel pitting corrosion resistance of 4 group samples with different concentrations of alloying elements was investigated using pitting corrosion tests in 10% FeCl3.The macrascopical morphology and corrosion rate of these samples after the experiment were tested.Additionally,the influence of alloying elements on pitting resistance equivalent was analyzed by testing the corrosion microstructural aspects and the distribution of alloying elements around the corrosion pits with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis.The results showed that the higher content of Cr and Mo,the better the pitting corrosion resistance of AISI 316 stainless steels.Conversely,Mn additions exerted an opposite effect,mainly due to the presence of MnS inclusions which acted as pitting initiators.According to the results,a new PRE equation which took the influence of Mn into account and put a higher weight on Cr was offered in this article.