摘要
金属材料在服役过程中,其表面裂纹的尖端会因受到应力作用而优先发生局部塑性变形;加之极化的共同作用,其与裂纹以外区域在腐蚀行为和腐蚀速率方面存在明显差异。本文使用自主设计的原位加载台,与扫描振动电极技术(SVET)和电化学工作站相结合,深入研究了酸性NaCl溶液中316L不锈钢裂纹尖端在应变和极化协同作用下的阳极溶解行为。结果表明:裂纹尖端是应力集中区,应变会导致裂纹尖端的钝化膜破裂及金属局部的快速阳极溶解。当金属处于开路电位或较低阳极极化电位下时,裂纹尖端新暴露的金属表面能快速钝化,导致总电流短暂上升然后迅速下降。在较高的阳极极化电位下,即使该电位处于316L不锈钢的钝化区,新暴露的金属表面也不能再次钝化,导致裂纹尖端局部位置持续的阳极溶解。在点蚀电位以上,316L表面会发生点蚀,由于应变新暴露的金属表面也不能再次钝化,导致裂纹尖端局部位置和点蚀处均为样品表面持续的阳极溶解区。
During the service life of metal materials,the tips of their surface cracks undergo local plastic deformation preferentially under the influence of stress.Additionally,the combined effect of polarization leads to significant differences in both corrosion behavior and corrosion rate between the crack tip and other zones.This research employed a custom-designed in-situ loading platform,integrated with scanning vibrating Electrode technology(SVET)and an electrochemical workstation,to thoroughly investigate the corrosion behavior at the tips of 316L stainless steel cracks in acidic NaCl solutions.Key conclusions are drawn as follows:The crack tip is a stress concentration zone where increased strain leads to the rupture of the passive film at the crack tip and rapid localized anodic dissolution of the metal.When the metal is at open-circuit potential or at a low anodic polarization potential,the newly exposed metal surface at the crack tip can rapidly passivate,causing the total current to briefly rise and then swiftly drop.At higher anodic polarization potentials,even if within the passivation range of 316L stainless steel,the newly exposed metal surface can’t repassivate,resulting in sustained anodic dissolution at localized crack tips.Above the pitting potential,not only do pitting corrosion occur on the 316L surface,but the newly exposed metal surfaces due to strain also fail to repassivate,making both the crack tips and pitting sites continual zones of anodic dissolution on the sample surface.
作者
王斯琰
张利涛
WANG Siyan;ZHANG Litao(School of Materials Science and Engineering,North University of China,Taiyuan 030051,China;Technology Center,Shanxi Taigang Stainless Steel Co.,Ltd.,Taiyuan 030003,China)
出处
《中北大学学报（自然科学版）》
CAS
2024年第2期247-256,共10页
Journal of North University of China(Natural Science Edition)
基金
山西省自然科学基金面上资助项目(202103021224219)。
