Zhang Leru, Yu Yanchong, Zhang Jinling, Mao Wangwang, Wang Shebin, Sun Zhonghua, Wan Yong
College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
HBIS Group Material Technology Research Institute, Shijiazhuang 052165, China.
Langmuir. 2024 Jul 23;40(29):15001-15012. doi: 10.1021/acs.langmuir.4c01313. Epub 2024 Jul 11.
Nb-microalloyed steels are widely used in construction engineering fields due to their excellent mechanical properties, but they face serious corrosion problems in service environments. Pitting corrosion is the severest form of corrosion, and the types of inclusions are the leading cause to induce pitting corrosion. A new strategy is proposed to enhance the corrosion resistance of steels by achieving a beneficial transformation of inclusions with Ce treatment. In this paper, two types of Nb-microalloyed steels (0% Ce and 0.0058% Ce steel) were prepared to study the modification effect on inclusions in industrial production. The spherical CaS•CA inclusions were modified to smaller ellipsoidal CeOS inclusions, and the proportion of inclusions (0-2 μm) increased significantly from 27 to 66%, while large inclusions (>6 μm) disappeared. A kinetic model of inclusion evolution was established. The results of electrochemical tests indicated that the corrosion potential was positively shifted, and the corrosion current was reduced after Ce treatment. Additionally, the number of defects in the passivation film was decreased, and the corrosion resistance of the steel was significantly improved. The addition of Ce changed the types of inclusions and reduced the number of pitting nucleation points, which led to a remarkable reduction in the number and size of pitting pits. The mechanism of pitting corrosion induced by different types of inclusions was further investigated, and a pitting corrosion model was modeled based on the immersion experiments. Research results provide theoretical support for enhancing the corrosion resistance of steel.
铌微合金钢因其优异的力学性能而广泛应用于建筑工程领域，但在服役环境中面临严重的腐蚀问题。点蚀是最严重的腐蚀形式，夹杂物类型是诱发点蚀的主要原因。提出了一种通过Ce处理实现夹杂物有益转变来提高钢耐蚀性的新策略。本文制备了两种铌微合金钢（0%Ce钢和0.0058%Ce钢），研究其在工业生产中对夹杂物的改性效果。球形CaS•CA夹杂物被改性为较小的椭球形CeOS夹杂物，尺寸为0-2μm的夹杂物比例从27%显著增加到66%，而尺寸大于6μm的大尺寸夹杂物消失。建立了夹杂物演变的动力学模型。电化学测试结果表明，Ce处理后腐蚀电位正向移动，腐蚀电流降低。此外，钝化膜中的缺陷数量减少，钢的耐蚀性显著提高。Ce的加入改变了夹杂物类型，减少了点蚀形核点数量，导致点蚀坑的数量和尺寸显著减少。进一步研究了不同类型夹杂物诱发点蚀的机理，并基于浸泡实验建立了点蚀模型。研究结果为提高钢的耐蚀性提供了理论支持。
