摘要
利用电化学及周期浸渍/干燥循环腐蚀实验方法研究了E690钢在模拟工业大气环境下的腐蚀行为,并采用扫描电镜(SEM)对腐蚀锈层进行了表征。电化学实验结果表明,E690在模拟工业大气环境下的自腐蚀电位正于Q235约30 m V,自腐蚀电流小于Q235约20μA,极化阻力约为Q235的1.5倍。周期浸渍/干燥循环腐蚀实验结果表明,E690在模拟工业大气环境下的耐蚀性明显优于Q235,其耐蚀性提高了155%。钢材耐蚀性的提高与锈层结构及合金元素分布情况有关。SEM及EDX(能谱分析)结果显示,E690锈层分为明显的内、外两层。外锈层疏松,内锈层致密。内锈层中Cr和Cu元素出现了明显的富集,从而提高了钢材的耐蚀性能。此外,内锈层中靠近基体的部位S,Ca和Si元素的含量均明显高于基体,这些硅酸钙类及硫化物类复合夹杂物成为了蚀坑的诱发因素。
The corrosion behavior corrosion - resistant E690 steel in industry ambient environment are simulated by electro - chemical and periodical submerge/dry recycle corrosion testing method, and the corrosion layer is characterized with scanning electron microscopic examination. The electro - chemical testing results show that the corrosion electric potential is just located at Q235 which is about 30 mV, the auto - corrosion current is lower than that of Q235, which is about 20 ~A and the polarization resistance is about 1.5 times of that of Q235. The periodical submerge/dry recycle corrosion testing show that the corrosion resistance performance of E690 steel in the simulated industry ambient environment is obviously better than that of E235 steel by 155%. The improvement of corrosion resistance of steel is related to the structure of corrosion layer and distribution of alloy elements. The results of SEM and DEX show that tile corrosion layers of E690 have internal and external rusts. The external corrosion layer is loose while the internal corrosion layer is dense. The accumulation of Cr and Cu elements in the internal rust has obviously improved the corrosion resistance of steels. In addition, the S, Ca and Si in the internal rust layer near the base metal are obviously higher than those of base metal. All complex impurities like calcium silicates and sulfides are the inducing factors of corrosion pits.
出处
《石油化工腐蚀与防护》
CAS
2016年第2期1-4,31,共5页
Corrosion & Protection In Petrochemical Industry
关键词
大气腐蚀
E690钢
锈层
ambient corrosion, E690 steel, rust layer
