控氮型不锈钢316LN在含氯介质中的点蚀行为

Pitting Corrosion Resistance of 316LN Stainless Steel in Chlorine-containing Aqueous Solution

针对N元素对奥氏体不锈钢抗点蚀能力的影响与其机理尚不明确的现状,以控氮型不锈钢316LN为研究对象,对其进行力学性能测试和电化学阻抗谱等电化学测试。结果表明316LN在室温下的力学性能及抗腐蚀性能均比不含氮的316L优越,但随着温度与介质浓度的提升,316LN的抗腐蚀性能存在明显的劣化;在室温和低介质浓度下,316LN的钝化膜阻抗普遍高于316L,显示在N元素和Cr、Mo等合金元素的协同下,316LN的表层钝化膜稳定性高于316L;同时N元素的转化产物NH_(4)^(+)或NO_(3)^(-)可有效抑制点蚀内部二次点蚀坑的形成,避免点蚀坑向纵深快速扩展。

In view of the current situation that the influence of N element on the pitting corrosion resistance of austenitic stainless steel and its mechanism are not clear,the mechanical properties and electrochemical impedance spectroscopy of nitrogen controlled stainless steel 316LN are tested.The results showed that the mechanical properties and corrosion resistance of 316LN at room temperature were superior to those of 316L stainless steel,but the corrosion resistance of 316LN stainless steel was degraded significantly with the increasing of temperature and medium concentration.At room temperature and low concentration of chloride ion,the impedance of the passivation film on 316LN stainless steel is higher than that of 316L stainless steel,which indicated that the stability of the passivation film on 316LN stainless steel is higher than that of 316L stainless steel under the synergistic effect among N,Cr and Mo.Meanwhile,the conversion products of NH_(4)^(+)or NO_(3)^(-)from N element can effectively inhibit the formation of secondary corrosion pits in 316LN stainless steel and avoid rapid propagation of corrosion pits in depth.