奥氏体321不锈钢在550℃静态铅铋共晶合金中的腐蚀行为

Corrosive Behavior of Austenitic 321 Stainless Steel in Static Lead-bismuth Eutectic Alloy at 550 ℃

奥氏体321不锈钢常用作核反应堆冷却剂主管道结构材料,铅铋共晶合金是第四代核能系统(GenⅣ)铅冷快堆冷却剂的主要候选材料。为研究321不锈钢与高温液态铅铋共晶合金的相容性,对321不锈钢在550℃液态铅铋共晶合金中的200、400、600 h腐蚀现象进行了研究。对不同腐蚀时间后腐蚀试样的表面和截面分别进行了XRD和SEM、EDS检测。结果发现:在321不锈钢试样表面产生了一种随腐蚀时间增加先生长后脱落的含O、Ti、Pb元素的化合物(Ti_2O和Pb_2O_3);在321不锈钢基体与铅铋共晶合金交界处会产生一层随腐蚀时间增加不断增厚的扩散层;321不锈钢在铅铋共晶合金中发生溶解腐蚀,在Fe、Cr元素不断向铅铋共晶合金中溶解时,伴随着Pb、Bi元素向基体中的渗透。

Austenitic 321 stainless steel is always used as the main pipeline material for nuclear reactor coolant. The lead-bismuth eutectic(LBE) alloy is a primary candidate coolant for the lead-cooled fast reactor for the fourth generation nuclear power system(Gen Ⅳ). The compatibility of 321 stainless steel and LBE alloy at 550 ℃ for 200, 400 and 600 h was studied. X-ray diffraction(XRD), scanning electron microscope(SEM) and energy dispersive spectrometry(EDS) were carried out on the surface and cross-section of corrosive samples with different corrosive time. A compound containing O, Ti and Pb elements(Ti2O and Pb2O3) is developed firstly on the surface of 321 stainless steel samples and peeled off with the increase of corrosive time successively. At the junction of 321 stainless steel matrix and LBE alloy, diffusion layer is thickened with time. In the process of corrosion, dissolution corrosion of 321 stainless steel occurs in the LBE alloy. Fe and Cr elements dissolve continuously in LBE alloy, meanwhile, Pb and Bi elements infiltrate into the base metal.