Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions
S355NL structural steel is extensively employed in bridges, ships, and power station equipment owing to its excellent tensile strength, weldability, and low-temperature toughness. However, pronounced fluctuations in its Charpy impact energy at low temperatures significantly compromise the reliabilit...
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2025-07-01
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| author | Jiandong Yang Bijun Xie Mingyue Sun |
| author_facet | Jiandong Yang Bijun Xie Mingyue Sun |
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| description | S355NL structural steel is extensively employed in bridges, ships, and power station equipment owing to its excellent tensile strength, weldability, and low-temperature toughness. However, pronounced fluctuations in its Charpy impact energy at low temperatures significantly compromise the reliability and service life of critical components. In this study, vacuum-induction-melted ingots of S355NL steel containing 0–0.086 wt.% rare earth cerium were prepared. The effects of Ce on microstructures, inclusions, and impact toughness were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and Charpy V-notch testing. The results indicate that appropriate Ce additions (0.0011–0.0049 wt.%) refine the average grain size from 5.27 μm to 4.88 μm, reduce the pearlite interlamellar spacing from 204 nm to 169 nm, and promote the transformation of large-size Al<sub>2</sub>O<sub>3</sub>-MnS composite inclusions into fine, spherical, Ce-rich oxysulfides. Charpy V-notch tests at –50 °C reveal that 0.0011 wt.% Ce enhances both longitudinal (269.7 J) and transverse (257.4 J) absorbed energies while minimizing anisotropy (E_t/E_l = 1.01). Conversely, excessive Ce addition (0.086 wt.%) leads to coarse inclusions and deteriorates impact performance. These findings establish an optimal Ce window (0.0011–0.0049 wt.%) for microstructural and inclusion engineering to enhance the low-temperature impact toughness of S355NL steel. |
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| institution | Kabale University |
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| spelling | doaj-art-81d337a8fd6a4aee8366b8d17d708e6f2025-08-20T03:58:31ZengMDPI AGMetals2075-47012025-07-0115780210.3390/met15070802Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and InclusionsJiandong Yang0Bijun Xie1Mingyue Sun2Shenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, ChinaShenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, ChinaShenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, ChinaS355NL structural steel is extensively employed in bridges, ships, and power station equipment owing to its excellent tensile strength, weldability, and low-temperature toughness. However, pronounced fluctuations in its Charpy impact energy at low temperatures significantly compromise the reliability and service life of critical components. In this study, vacuum-induction-melted ingots of S355NL steel containing 0–0.086 wt.% rare earth cerium were prepared. The effects of Ce on microstructures, inclusions, and impact toughness were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and Charpy V-notch testing. The results indicate that appropriate Ce additions (0.0011–0.0049 wt.%) refine the average grain size from 5.27 μm to 4.88 μm, reduce the pearlite interlamellar spacing from 204 nm to 169 nm, and promote the transformation of large-size Al<sub>2</sub>O<sub>3</sub>-MnS composite inclusions into fine, spherical, Ce-rich oxysulfides. Charpy V-notch tests at –50 °C reveal that 0.0011 wt.% Ce enhances both longitudinal (269.7 J) and transverse (257.4 J) absorbed energies while minimizing anisotropy (E_t/E_l = 1.01). Conversely, excessive Ce addition (0.086 wt.%) leads to coarse inclusions and deteriorates impact performance. These findings establish an optimal Ce window (0.0011–0.0049 wt.%) for microstructural and inclusion engineering to enhance the low-temperature impact toughness of S355NL steel.https://www.mdpi.com/2075-4701/15/7/802S355NL steelrare earth microalloyinggrain refinementinclusion modificationimpact toughness |
| spellingShingle | Jiandong Yang Bijun Xie Mingyue Sun Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions Metals S355NL steel rare earth microalloying grain refinement inclusion modification impact toughness |
| title | Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions |
| title_full | Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions |
| title_fullStr | Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions |
| title_full_unstemmed | Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions |
| title_short | Cerium Addition Enhances Impact Energy Stability in S355NL Steel by Tailoring Microstructure and Inclusions |
| title_sort | cerium addition enhances impact energy stability in s355nl steel by tailoring microstructure and inclusions |
| topic | S355NL steel rare earth microalloying grain refinement inclusion modification impact toughness |
| url | https://www.mdpi.com/2075-4701/15/7/802 |
| work_keys_str_mv | AT jiandongyang ceriumadditionenhancesimpactenergystabilityins355nlsteelbytailoringmicrostructureandinclusions AT bijunxie ceriumadditionenhancesimpactenergystabilityins355nlsteelbytailoringmicrostructureandinclusions AT mingyuesun ceriumadditionenhancesimpactenergystabilityins355nlsteelbytailoringmicrostructureandinclusions |