Abstract Pitting corrosion behavior of Ce treated HSLA steels induced by sulfide inclusions in 3.5wt% NaCl solution was investigated with potentiodynamic polarization and immersion corrosion test. The results showed that Ce added steels exhibited better pitting corrosion resistance with lower corrosion current density and bigger pitting potential compared with steel without Ce, which was mainly attributed to optimized characteristics of spherical Ce-oxysulfide inclusions with less number density, smaller average size and lower pitting corrosion susceptibility. The spherical Ce2O2S inclusions precipitated on the surface of CeAlO3 inclusions in the Ce added steels induced pits with bigger opening mouth and shallow depth, reducing their tendency of extension to go deeper due to occlusion corrosion battery in the pitting holes. Furthermore, corrosion inhibitor Ce(OH)3 generated by Ce2O2S hydration can weaken electrochemical corrosion of the matrix micro-region around the pits. To avoid harmful bigger inclusions, Ce content in steels should be regulated within reasonable range, 0.015 wt% Ce in present steels effectively modified inclusions to acquire the best pitting corrosion resistance of the steels.

中文翻译：

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硫化物夹杂物在 3.5 wt% NaCl 溶液中对铈处理的 HSLA 钢的点蚀行为

摘要 采用动电位极化和浸没腐蚀试验研究了硫化物夹杂物在3.5wt% NaCl溶液中对Ce处理HSLA钢的点蚀行为。结果表明，与不含 Ce 的钢相比，添加 Ce 的钢表现出更好的耐点蚀性，具有更低的腐蚀电流密度和更大的点蚀电位，这主要是由于球形 Ce-氧硫化物夹杂物的数量密度更小、平均尺寸更小和更低点腐蚀敏感性。添加Ce钢的CeAlO3夹杂物表面析出的球形Ce2O2S夹杂物诱发了开口较大、深度较浅的凹坑，减少了由于点蚀孔中的咬合腐蚀电池而导致的凹坑向深部延伸的趋势。此外，Ce2O2S水化产生的缓蚀剂Ce(OH)3可以减弱凹坑周围基体微区的电化学腐蚀。为了避免有害的较大夹杂物，钢中的Ce含量应控制在合理范围内，现有钢中0.015wt%的Ce有效地改性夹杂物，使钢获得最佳的耐点蚀性能。