430不锈钢在550℃流动Pb-Bi合金中的腐蚀行为

Corrosion Behavior of 430 Stainless Steel in Flowing Pb-Bi Alloy at 550℃

为了研究430不锈钢(430ss)与高温Pb-Bi合金的相容性,将430ss浸没在550℃、2.98m/s的液态Pb-Bi合金中进行200h、400h和600h的腐蚀试验。利用XRD、SEM和EDS进行检测,分别研究经腐蚀不同时间后试样表面和截面的腐蚀现象。结果表明:腐蚀试样表面首先产生不规则形状的由Fe、Cr、O三种元素组成的氧化物,而后逐渐生长并汇集成相对均匀的氧化层;氧化层呈双层结构,分别为外氧化层和内氧化层,外氧化层主要由疏松多孔的Fe3O4以及部分渗入的Pb-Bi组成,内氧化层主要由致密的Fe-Cr尖晶石(Fe,Cr)3O4组成;随腐蚀时间的延长(0~600h),内外氧化层厚度不断增加并变得相对均匀;在腐蚀过程中同时发生溶解腐蚀和氧化腐蚀。

In order to study the corrosion behavior of430 stainless steel(430ss)in flowing Pb-Bi alloy at high temperature,corrosion tests of430ss were performed in the LBE at 550℃for 200 h,400 h and 600 h with relative velocity of 2.98 m/s.X-ray diffraction(XRD),scanning electron microscope(SEM)and energy dispersive spectrometry(EDS)were carried out to detect the corrosion characteristics of the surface and cross-section of the etched samples.It is found that a compound containing Fe,Cr and O elements formed on the surface of the corrosion samples.The shape of the compound was irregular firstly,and then,the compound grew gradually to assemble the homogeneous oxide layer.The oxide layer could be classified to an outer oxide layer and an inner oxide layer.The double-layer oxide films were composed of magnetite Fe3O4 outer layer with penetration of Pb-Bi and Fe-Cr spinel(Fe,Cr)3O4 inner layer.The outer oxide layer was porous while the inner one was compact.With the increase of corrosion time(0—600 h),the thickness of oxide layers became thicker gradually.The metal exhibited dissolution-corrosion and oxidation-corrosion during the corrosion process.