模拟停工装置内潮湿环境,对20 号钢、16MnR、Cr5Mo和304 不锈钢等4 种典型材质,在氮气置换保护条件下的腐蚀进行试验,考察了氧含量对4 种材质腐蚀的影响.利用挂片失重法、3D轮廓仪和XRD等手段对试样进行了腐蚀速率分析、腐蚀形貌观察和腐蚀产物组成分析.结果表明:气相潮湿环境下,随着氧含量的增加,碳钢腐蚀速率先降低后平稳增加,Cr5Mo和304 不锈钢的腐蚀速率均稳定保持在较低的水平;液相环境下,当氧体积分数大于 1. 0%时碳钢和铬钼钢腐蚀速率有升高的趋势;氧体积分数为0. 5%～1. 0%时各材质在气液两种环境下的腐蚀速率相差不大;碳钢和铬钼钢的宏观形貌基本一致,腐蚀产物主要是疏松的 γ-FeOOH 和致密的Fe3O4,金属基体腐蚀表现为蚀坑和溃疡状腐蚀;304 不锈钢未见明显腐蚀,仍保持金属光泽.选取某企业停工装置的典型部位进行了周期 114 天的现场挂片试验,结果表明,在氧体积分数为0. 5%的情况下,各部位的停工保护效果良好.%The oxygen corrosion behaviors of No. 20,16MnR,Cr5Mo,and 304 steel in nitrogen pro- tection were studied under the simulated wet environment. The corrosion rate,corrosion appearance and the composition of corrosion products were investigated by coupon weight-loss method,3D profilometry and X-Ray(XRD),respectively. The results showed that,in the humid gas atmosphere,the trend of cor-rosion rate for carbon steel is to rise first followed by a steady increase with increasing oxygen content;the corrosion rates of Cr5Mo and 304 stainless steels both are stable at a low level. In the liquid phase, the corrosion rates of carbon steel and chromium-molybdenum steel increase obviously when oxygen con-tent reaches to 1. 0%. There is small difference of material corrosion rates when the oxygen content changes in the range of 0. 5%-1. 0% either in gas or liquid phase. The corrosion characteristics of car-bon steel and chromium-molybdenum steel are basically the same. The corrosion products mainly consist of loose γ-FeOOH and tight Fe3O4,with metal ulcerated and etched. The 304 stainless steel still main-tains the metallic luster and has no obvious corrosion. Typical sites of shutdown equipment were selected to do a corrosion test for 114 d,and the protective effect is fine in the environment with 0. 5% oxygen content.
展开▼
