Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process
Advanced high-strength steels (AHSS) have a wide range of applications in equipment safety and lightweight design, and enhancing the strength of AHSS to the ultra-high level of 2 GPa is currently a key focus. In this study, a new process of thermo-mechanical control process followed by direct quench...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
| Language: | English |
| Published: |
2024
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| Online Access: | https://hdl.handle.net/10356/173760 |
| _version_ | 1811694170129039360 |
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| author | Niu, Gang Jin, Donghao Wang, Yong Chen, Haoxiu Gong, Na Wu, Huibin |
| author2 | School of Materials Science and Engineering |
| author_facet | School of Materials Science and Engineering Niu, Gang Jin, Donghao Wang, Yong Chen, Haoxiu Gong, Na Wu, Huibin |
| author_sort | Niu, Gang |
| collection | NTU |
| description | Advanced high-strength steels (AHSS) have a wide range of applications in equipment safety and lightweight design, and enhancing the strength of AHSS to the ultra-high level of 2 GPa is currently a key focus. In this study, a new process of thermo-mechanical control process followed by direct quenching and partitioning (TMCP-DQP) was developed based on Fe-0.4C-1Mn-0.6Si (wt.%) low-alloy steel, and the effects of microstructure evolution on mechanical properties under TMCP-DQP process and conventional hot rolled quenched and tempered process (HR-QT) were comparatively studied. The results show that the TMCP-DQP process not only shortened the processing steps but also achieved outstanding comprehensive mechanical properties. The TMCP-DQP steel exhibited a tensile strength of 2.23 GPa, accompanied by 11.9% elongation and a Brinell hardness of 624 HBW, with an impact toughness of 28.5 J at -20 °C. In contrast, the HR-QT steel exhibited tensile strengths ranging from 2.16 GPa to 1.7 GPa and elongations between 5.2% and 12.2%. The microstructure of TMCP-DQP steel primarily consisted of lath martensite, containing thin-film retained austenite (RA), nanoscale rod-shaped carbides, and a minor number of nanoscale twins. The volume fraction of RA reached 7.7%, with an average carbon content of 7.1 at.% measured by three-dimensional atom probe tomography (3DAP). Compared with the HR-QT process, the TMCP-DQP process resulted in a finer microstructure, with a prior austenite grain (PAG) size of 11.91 μm, forming packets and blocks with widths of 5.12 μm and 1.63 μm. The TMCP-DQP process achieved the ultra-high strength of low-alloy steel through the synergistic effects of grain refinement, dislocation strengthening, and precipitation strengthening. The dynamic partitioning stage stabilized the RA through carbon enrichment, while the relaxation stage reduced a small portion of the dislocations generated by thermal deformation, and the self-tempering stage eliminated internal stresses, all guaranteeing considerable ductility and toughness. The TMCP-DQP process may offer a means for industries to streamline their manufacturing processes and provide a technological reference for producing 2.2 GPa grade AHSS. |
| first_indexed | 2024-10-01T07:03:19Z |
| format | Journal Article |
| id | ntu-10356/173760 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:03:19Z |
| publishDate | 2024 |
| record_format | dspace |
| spelling | ntu-10356/1737602024-03-01T15:46:25Z Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process Niu, Gang Jin, Donghao Wang, Yong Chen, Haoxiu Gong, Na Wu, Huibin School of Materials Science and Engineering Engineering 2.2 GPa ultra-high strength steel TMCP-DQP process Advanced high-strength steels (AHSS) have a wide range of applications in equipment safety and lightweight design, and enhancing the strength of AHSS to the ultra-high level of 2 GPa is currently a key focus. In this study, a new process of thermo-mechanical control process followed by direct quenching and partitioning (TMCP-DQP) was developed based on Fe-0.4C-1Mn-0.6Si (wt.%) low-alloy steel, and the effects of microstructure evolution on mechanical properties under TMCP-DQP process and conventional hot rolled quenched and tempered process (HR-QT) were comparatively studied. The results show that the TMCP-DQP process not only shortened the processing steps but also achieved outstanding comprehensive mechanical properties. The TMCP-DQP steel exhibited a tensile strength of 2.23 GPa, accompanied by 11.9% elongation and a Brinell hardness of 624 HBW, with an impact toughness of 28.5 J at -20 °C. In contrast, the HR-QT steel exhibited tensile strengths ranging from 2.16 GPa to 1.7 GPa and elongations between 5.2% and 12.2%. The microstructure of TMCP-DQP steel primarily consisted of lath martensite, containing thin-film retained austenite (RA), nanoscale rod-shaped carbides, and a minor number of nanoscale twins. The volume fraction of RA reached 7.7%, with an average carbon content of 7.1 at.% measured by three-dimensional atom probe tomography (3DAP). Compared with the HR-QT process, the TMCP-DQP process resulted in a finer microstructure, with a prior austenite grain (PAG) size of 11.91 μm, forming packets and blocks with widths of 5.12 μm and 1.63 μm. The TMCP-DQP process achieved the ultra-high strength of low-alloy steel through the synergistic effects of grain refinement, dislocation strengthening, and precipitation strengthening. The dynamic partitioning stage stabilized the RA through carbon enrichment, while the relaxation stage reduced a small portion of the dislocations generated by thermal deformation, and the self-tempering stage eliminated internal stresses, all guaranteeing considerable ductility and toughness. The TMCP-DQP process may offer a means for industries to streamline their manufacturing processes and provide a technological reference for producing 2.2 GPa grade AHSS. Agency for Science, Technology and Research (A*STAR) Published version G.N., D.J., N.G. and H.W. appreciate the support from the National Natural Science Foundation of China (Grant No. 52304389). G.N. appreciates the support from the National Natural Science Foundation of China (Grant No. 52304389) and the China Postdoctoral Science Foundation (2022M720402). N.G. appreciates the support from the Structural Metal Alloy Program (SMAP), Grant No. A18B1b0061, and Manufacturing of Multi-Material Net-Shape Parts with Heterogeneous Properties (MMNH), Grant No. M22K5a0045 in A*STAR. 2024-02-26T07:48:38Z 2024-02-26T07:48:38Z 2023 Journal Article Niu, G., Jin, D., Wang, Y., Chen, H., Gong, N. & Wu, H. (2023). Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process. Materials, 16(24), 7533-. https://dx.doi.org/10.3390/ma16247533 1996-1944 https://hdl.handle.net/10356/173760 10.3390/ma16247533 38138675 2-s2.0-85180618088 24 16 7533 en Materials © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). application/pdf |
| spellingShingle | Engineering 2.2 GPa ultra-high strength steel TMCP-DQP process Niu, Gang Jin, Donghao Wang, Yong Chen, Haoxiu Gong, Na Wu, Huibin Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process |
| title | Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process |
| title_full | Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process |
| title_fullStr | Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process |
| title_full_unstemmed | Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process |
| title_short | Achieving 2.2 GPa ultra-high strength in low-alloy steel using a direct quenching and partitioning process |
| title_sort | achieving 2 2 gpa ultra high strength in low alloy steel using a direct quenching and partitioning process |
| topic | Engineering 2.2 GPa ultra-high strength steel TMCP-DQP process |
| url | https://hdl.handle.net/10356/173760 |
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