干湿交替环境下气体组成对低合金钢腐蚀行为的影响

参照国际海事组织(IMO)所规定的模拟货油舱上甲板(COT)试验条件,利用专门建立的模拟上甲板环境腐蚀试验装置,研究了货油舱上甲板环境中,不同气体成分对低合金钢的腐蚀行为的影响.观察了低合金钢在不同成分的气体中基体和腐蚀产物的宏观和微观形貌,测定了锈层的物相组成.研究结果显示,在干湿交替环境下,低合金钢在SO2+ CO2+O2+N2气体中的腐蚀速率是H2S+ N2气体中的5.7倍;H2S+ N2环境下腐蚀产物为FeS,SO2+CO2+ O2+ N2环境下腐蚀产物为α-FeOOH、Fe2O3、FeSO4,且基体表面存在沿晶界发生的沟渠状和酸性液滴造成的斑状腐蚀形貌.

Effect of gas composition on the corrosion behavior of low alloy steel in wet-dry cycling environment

According to the regulations of the International Maritime Organization (IMO) about the test conditions of simulated upper deck in cargo oil tank (COT),the impact of different gas compositions on the corrosion behavior of low alloy steel under the environment of upper deck in cargo oil tank was investigated with specially established test devices.The macro morphologies of matrix and corrosion products were researched,and the phase composition of rust layer was determined.The results indicate that the corrosion rate of low alloy steel in SO2 +CO2 +O2 +N2 is 5.7 times of that in H2S+ N2 environment.The corrosion product in H2S + N2 is FeS only,while the corrosion products in SO2 +CO2 +O2+N2 are α-FeOOH,Fe2O3,FeSO4.In SO2 +CO2 +O2 +N2,on the surface of substrate,there are corrosion morphologies of ditches along grain boundary and spots which are the result of acid droplets.