拉应力下T91钢在550℃液态铅铋中的腐蚀行为

Corrosion behavior of T91 steel in liquid lead-bismuth eutectic at 550℃ under different tensile stresses

为有效评估T91钢在液态铅铋合金(lead-bismuth eutectic,LBE)中不同拉应力下的腐蚀行为,采用小锥度圆锥体试样,开展了0~180MPa下T91钢在550℃、1×10^(-6) wt%氧浓度LBE中的腐蚀实验.结果表明:(Fe,Cr)_3O_4层和内氧化层始终存在,而Fe_3O_4层在拉应力作用下出现严重的脱落,且Fe3O4碎片随应力增加而变小;(Fe,Cr)_3O_4层由于Cr富集度不同而呈现出两层亚结构;随着拉应力的增加,裂纹数量增加,尺寸变大,并不断向基体方向扩展,到180 MPa时已贯穿整个(Fe,Cr)_3O_4层.此外,各氧化层厚度随应力增加而增加,但增厚速率不断降低.

To efficiently evaluate the corrosion behavior of T91 steel in lead-bismuth eutectic （LBE） under different stresses, a corrosion experiment of small tapered conical specimen of T91 in LBE with an oxygen concentration of 1×10^- 6 wt% at 550 ℃ under 0--180 MPa was carried out. The results showed that the （ Fe, Cr） 3 O4 and internal oxidation zone always exist, but the Fe3O4 peels off severely under tensile stress, and its fragments become smaller with the increase of stress; （Fe,Cr）3O4 has two sub-layers, which is caused by different Cr enrichments; As the tensile stress increases, the cracks increase in number and size, extending continuously to the matrix direction, running through the whole （Fe,Cr）3O4 by the time the tensile stress reaches 180 MPa. Moreover, with the tensile stress increasing, the thickness of each oxide layer increases, but the rate of inerassation decreases constantly.