Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels
The high-temperature mechanical stability of structural steels is critical for fire-resistant applications, yet the individual contributions of microalloying elements remain incompletely understood. In this study, we systematically investigated the strengthening mechanisms of three key microalloying...
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Elsevier
2025-07-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785425015662 |
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| author | Hyungkwon Park Hyo-Haeng Jo Seong Hoon Kim Chiwon Kim Joonoh Moon Jun-Ho Chung Bong Ho Lee Chang-Hoon Lee |
| author_facet | Hyungkwon Park Hyo-Haeng Jo Seong Hoon Kim Chiwon Kim Joonoh Moon Jun-Ho Chung Bong Ho Lee Chang-Hoon Lee |
| author_sort | Hyungkwon Park |
| collection | DOAJ |
| description | The high-temperature mechanical stability of structural steels is critical for fire-resistant applications, yet the individual contributions of microalloying elements remain incompletely understood. In this study, we systematically investigated the strengthening mechanisms of three key microalloying elements–Nb, Ti, and V–in low-Mo fire-resistant steel. Each element was independently added to a 0.15Mo-base steel at varying concentrations, and tensile tests were conducted at room temperature (RT) and 600 °C. Microstructural features were characterized in detail using atom probe tomography. Ti enhanced the yield strength (YS) at both temperatures via the formation of (Ti,Mo)(C,N) precipitates, but excessive Ti reduced the YS ratio (σ600oC/σRT) due to solute depletion and precipitate coarsening. V demonstrated minimal precipitation and limited impact at RT, but its linear contribution to high-temperature strength is attributed to secondary hardening by VC. Nb yielded the most consistent strengthening across both temperatures through the combined effects of (Nb,Mo)C precipitation, Nb–C clustering, solid solution strengthening, and bainitic transformation. These findings clarify the element-specific mechanisms governing fire-resistant behavior and suggest that optimized microalloying strategies can enable steels with superior strength retention at elevated temperatures. |
| format | Article |
| id | doaj-art-2dbe7024c19848a6bec661ac9a2ae4f3 |
| institution | Kabale University |
| issn | 2238-7854 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
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| series | Journal of Materials Research and Technology |
| spelling | doaj-art-2dbe7024c19848a6bec661ac9a2ae4f32025-08-20T03:30:04ZengElsevierJournal of Materials Research and Technology2238-78542025-07-01372144215110.1016/j.jmrt.2025.06.144Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steelsHyungkwon Park0Hyo-Haeng Jo1Seong Hoon Kim2Chiwon Kim3Joonoh Moon4Jun-Ho Chung5Bong Ho Lee6Chang-Hoon Lee7Extreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaDepartment of Materials Science and Engineering, Changwon National University, Republic of KoreaHyundai Steel Company, Incheon, 22525, Republic of KoreaAdvanced Analysis Team, Institute of Next-generation Semiconductor Convergence Technology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, 42988, Republic of Korea; Corresponding author.Extreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of Korea; Corresponding author.The high-temperature mechanical stability of structural steels is critical for fire-resistant applications, yet the individual contributions of microalloying elements remain incompletely understood. In this study, we systematically investigated the strengthening mechanisms of three key microalloying elements–Nb, Ti, and V–in low-Mo fire-resistant steel. Each element was independently added to a 0.15Mo-base steel at varying concentrations, and tensile tests were conducted at room temperature (RT) and 600 °C. Microstructural features were characterized in detail using atom probe tomography. Ti enhanced the yield strength (YS) at both temperatures via the formation of (Ti,Mo)(C,N) precipitates, but excessive Ti reduced the YS ratio (σ600oC/σRT) due to solute depletion and precipitate coarsening. V demonstrated minimal precipitation and limited impact at RT, but its linear contribution to high-temperature strength is attributed to secondary hardening by VC. Nb yielded the most consistent strengthening across both temperatures through the combined effects of (Nb,Mo)C precipitation, Nb–C clustering, solid solution strengthening, and bainitic transformation. These findings clarify the element-specific mechanisms governing fire-resistant behavior and suggest that optimized microalloying strategies can enable steels with superior strength retention at elevated temperatures.http://www.sciencedirect.com/science/article/pii/S2238785425015662Fire-resistant steelHigh-temperature strengthMicroalloyingAtomic probe tomographyStrengthening mechanism |
| spellingShingle | Hyungkwon Park Hyo-Haeng Jo Seong Hoon Kim Chiwon Kim Joonoh Moon Jun-Ho Chung Bong Ho Lee Chang-Hoon Lee Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels Journal of Materials Research and Technology Fire-resistant steel High-temperature strength Microalloying Atomic probe tomography Strengthening mechanism |
| title | Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels |
| title_full | Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels |
| title_fullStr | Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels |
| title_full_unstemmed | Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels |
| title_short | Distinct roles of Nb, Ti, and V microalloying elements on the fire resistance of low-Mo steels |
| title_sort | distinct roles of nb ti and v microalloying elements on the fire resistance of low mo steels |
| topic | Fire-resistant steel High-temperature strength Microalloying Atomic probe tomography Strengthening mechanism |
| url | http://www.sciencedirect.com/science/article/pii/S2238785425015662 |
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