Scholarlink

<p>The early-stage corrosion behavior of bare and pre-oxidized SS 316L was investigated in oxygen-controlled flowing liquid lead (Pb) at 400&#xa0;°C under LFR-relevant conditions. Experiments were conducted at an oxygen concentration of ~ 5 × 10<sup>⁻7</sup>&#xa0;wt% and a flow velocity of ~ 1.25&#xa0;m/s for exposure durations up to 1000&#xa0;h. A combination of SEM/EDS, XRD, Raman spectroscopy, and TEM was employed to characterize oxide evolution and assess corrosion mechanisms. Bare SS 316L developed a thin in-situ oxide scale that evolved from a non-uniform layer (~ 200&#xa0;nm) after 500&#xa0;h to a more uniform thickness (~ 300&#xa0;nm) after 1000&#xa0;h. Phase analysis identified this scale predominantly as an (Fe, Cr)<sub>3</sub>O<sub>4</sub> spinel. No evidence of Pb penetration into the substrate or Ni depletion was observed, indicating that the oxide remained adherent and provided a partial diffusion barrier under the present conditions. Pre-oxidation at 800&#xa0;°C for 60&#xa0;h produced a duplex oxide structure consisting of an inner Cr<sub>2</sub>O<sub>3</sub> layer and an outer (Cr, Mn)<sub>3</sub>O<sub>4</sub> spinel layer (~ 0.75 ± 0.2&#xa0;µm). During Pb exposure, the outer spinel layer underwent progressive degradation, characterized by thinning, Pb infiltration, and localized delamination. In contrast, the inner Cr<sub>2</sub>O<sub>3</sub> layer remained dense, continuous, and adherent up to 1000&#xa0;h, effectively limiting Pb ingress into the substrate. The results suggest that corrosion of SS 316L in liquid Pb involves competing oxide growth and dissolution processes, with the stability of Cr-rich oxide playing a key role in controlling degradation. Compared to the bare alloy, pre-oxidized SS 316L exhibited improved early-stage corrosion resistance by preserving a stable inner Cr<sub>2</sub>O<sub>3</sub> layer and delaying transition toward less protective Fe-rich oxides. This study provides mechanistic insight into oxide evolution in pure liquid Pb at 400&#xa0;°C under flowing conditions and highlights the importance of engineered pre-oxidation treatments for enhancing the corrosion performance of structural materials in lead-cooled fast reactor systems.</p> Graphical Abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Early-Stage Corrosion Behavior of Bare and Pre-oxidized SS 316L in an LFR-Relevant Flowing Liquid Pb Environment

  • 期刊论文

  • 发表日期：

    2026年4月29日

查看全文
  • Paulson Varghese,
  • Matthew Kevin Margeson,
  • Jung-Kun Lee

摘要

The early-stage corrosion behavior of bare and pre-oxidized SS 316L was investigated in oxygen-controlled flowing liquid lead (Pb) at 400 °C under LFR-relevant conditions. Experiments were conducted at an oxygen concentration of ~ 5 × 10⁻7 wt% and a flow velocity of ~ 1.25 m/s for exposure durations up to 1000 h. A combination of SEM/EDS, XRD, Raman spectroscopy, and TEM was employed to characterize oxide evolution and assess corrosion mechanisms. Bare SS 316L developed a thin in-situ oxide scale that evolved from a non-uniform layer (~ 200 nm) after 500 h to a more uniform thickness (~ 300 nm) after 1000 h. Phase analysis identified this scale predominantly as an (Fe, Cr)3O4 spinel. No evidence of Pb penetration into the substrate or Ni depletion was observed, indicating that the oxide remained adherent and provided a partial diffusion barrier under the present conditions. Pre-oxidation at 800 °C for 60 h produced a duplex oxide structure consisting of an inner Cr2O3 layer and an outer (Cr, Mn)3O4 spinel layer (~ 0.75 ± 0.2 µm). During Pb exposure, the outer spinel layer underwent progressive degradation, characterized by thinning, Pb infiltration, and localized delamination. In contrast, the inner Cr2O3 layer remained dense, continuous, and adherent up to 1000 h, effectively limiting Pb ingress into the substrate. The results suggest that corrosion of SS 316L in liquid Pb involves competing oxide growth and dissolution processes, with the stability of Cr-rich oxide playing a key role in controlling degradation. Compared to the bare alloy, pre-oxidized SS 316L exhibited improved early-stage corrosion resistance by preserving a stable inner Cr2O3 layer and delaying transition toward less protective Fe-rich oxides. This study provides mechanistic insight into oxide evolution in pure liquid Pb at 400 °C under flowing conditions and highlights the importance of engineered pre-oxidation treatments for enhancing the corrosion performance of structural materials in lead-cooled fast reactor systems.

Graphical Abstract