The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties
In this study, the refinement of two microstructures was controlled in medium carbon 25Cr2Ni3MoV steel via multi-step tempering and partition (MTP) to achieve high cryogenic strength–ductility combinations. Microstructure evolution, the distribution of stress concentration, and microcrack formation...
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MDPI AG
2024-01-01
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| Online Access: | https://www.mdpi.com/1996-1944/17/2/518 |
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| author | Ye Chen Ran Chen Yanchen Yao Na Min Wei Li Anna Diao |
| author_facet | Ye Chen Ran Chen Yanchen Yao Na Min Wei Li Anna Diao |
| author_sort | Ye Chen |
| collection | DOAJ |
| description | In this study, the refinement of two microstructures was controlled in medium carbon 25Cr2Ni3MoV steel via multi-step tempering and partition (MTP) to achieve high cryogenic strength–ductility combinations. Microstructure evolution, the distribution of stress concentration, and microcrack formation and propagation during cryogenic Charpy impact testing were investigated. Compared with their performance in the quenching and tempering states (QT), the MTP steels showed a significant improvement in yield strength (1300 MPa), total elongation (25%), and impact toughness (>25 J) at liquid nitrogen temperature (LNT). The strengthening contributions mainly originated from the high dislocation density and refinement cementite (size: 70 nm) in the martensite lath (width: 1.5 μm) introduced by refined reversed austenite and its latter decomposition. The instrumented Charpy impact results indicated that cracks nucleated in the primary austenite grain (PAG) boundary for two steels due to the strain concentration band preferring to appear near PAGs, while cracks in the QT and MTP samples propagated along the PAGs and high-angle grain boundary (HAGB), respectively. The crystallized plasticity finite element simulation revealed that the PAG boundary with cementite precipitates of large size (>200 nm) was less able to dissipate crack propagation energy than the HAGBs by continuously forming a high strain concentration area, thus leading to the low-impact toughness of the QT steel. |
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| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-08T10:42:31Z |
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| spelling | doaj.art-b04abab37b7745d8ac0801f81c2a2d1e2024-01-26T17:30:44ZengMDPI AGMaterials1996-19442024-01-0117251810.3390/ma17020518The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength PropertiesYe Chen0Ran Chen1Yanchen Yao2Na Min3Wei Li4Anna Diao5Shanghai Key Laboratory of Material Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240, ChinaThe State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, ChinaShanghai Marine Diesel Engine Research Institute, Shanghai 201108, ChinaKey Laboratory for Microstructures, Shanghai University, Shanghai 200444, ChinaShanghai Key Laboratory of Material Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240, ChinaShanghai Marine Diesel Engine Research Institute, Shanghai 201108, ChinaIn this study, the refinement of two microstructures was controlled in medium carbon 25Cr2Ni3MoV steel via multi-step tempering and partition (MTP) to achieve high cryogenic strength–ductility combinations. Microstructure evolution, the distribution of stress concentration, and microcrack formation and propagation during cryogenic Charpy impact testing were investigated. Compared with their performance in the quenching and tempering states (QT), the MTP steels showed a significant improvement in yield strength (1300 MPa), total elongation (25%), and impact toughness (>25 J) at liquid nitrogen temperature (LNT). The strengthening contributions mainly originated from the high dislocation density and refinement cementite (size: 70 nm) in the martensite lath (width: 1.5 μm) introduced by refined reversed austenite and its latter decomposition. The instrumented Charpy impact results indicated that cracks nucleated in the primary austenite grain (PAG) boundary for two steels due to the strain concentration band preferring to appear near PAGs, while cracks in the QT and MTP samples propagated along the PAGs and high-angle grain boundary (HAGB), respectively. The crystallized plasticity finite element simulation revealed that the PAG boundary with cementite precipitates of large size (>200 nm) was less able to dissipate crack propagation energy than the HAGBs by continuously forming a high strain concentration area, thus leading to the low-impact toughness of the QT steel.https://www.mdpi.com/1996-1944/17/2/51825Cr2Ni3MoV steelmulti-step tempering and partitioncryogenic mechanical propertyCPFEM |
| spellingShingle | Ye Chen Ran Chen Yanchen Yao Na Min Wei Li Anna Diao The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties Materials 25Cr2Ni3MoV steel multi-step tempering and partition cryogenic mechanical property CPFEM |
| title | The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties |
| title_full | The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties |
| title_fullStr | The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties |
| title_full_unstemmed | The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties |
| title_short | The Effect of Multi-Step Tempering and Partition Heat Treatment on 25Cr2Ni3MoV Steel’s Cryogenic Strength Properties |
| title_sort | effect of multi step tempering and partition heat treatment on 25cr2ni3mov steel s cryogenic strength properties |
| topic | 25Cr2Ni3MoV steel multi-step tempering and partition cryogenic mechanical property CPFEM |
| url | https://www.mdpi.com/1996-1944/17/2/518 |
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