The influence of relaxation time on the microstructure and properties of thin-gauge 450 MPa grade high-strength steel

HAN Chufei; DONG Yi; SHI Xiaoguang; SUN Chengqian; WANG Junxiong; LI Zhi; XU Haijian

doi:10.7513/j.issn.1004-7638.2025.06.023

Volume 46 Issue 6

Dec. 2025

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HAN Chufei, DONG Yi, SHI Xiaoguang, SUN Chengqian, WANG Junxiong, LI Zhi, XU Haijian. The influence of relaxation time on the microstructure and properties of thin-gauge 450 MPa grade high-strength steel[J]. IRON STEEL VANADIUM TITANIUM, 2025, 46(6): 186-190, 200. doi: 10.7513/j.issn.1004-7638.2025.06.023

Citation:

HAN Chufei, DONG Yi, SHI Xiaoguang, SUN Chengqian, WANG Junxiong, LI Zhi, XU Haijian. The influence of relaxation time on the microstructure and properties of thin-gauge 450 MPa grade high-strength steel[J]. IRON STEEL VANADIUM TITANIUM, 2025, 46(6): 186-190, 200. doi: 10.7513/j.issn.1004-7638.2025.06.023

Citation:

HAN Chufei, DONG Yi, SHI Xiaoguang, SUN Chengqian, WANG Junxiong, LI Zhi, XU Haijian. The influence of relaxation time on the microstructure and properties of thin-gauge 450 MPa grade high-strength steel[J]. IRON STEEL VANADIUM TITANIUM, 2025, 46(6): 186-190, 200. doi: 10.7513/j.issn.1004-7638.2025.06.023

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The influence of relaxation time on the microstructure and properties of thin-gauge 450 MPa grade high-strength steel

doi: 10.7513/j.issn.1004-7638.2025.06.023

HAN Chufei^{1, 2, 3
,},
DONG Yi^{1, 2},
SHI Xiaoguang^{1, 2},
SUN Chengqian^{1, 2},
WANG Junxiong^{1, 2},
LI Zhi^{1, 2},
XU Haijian^{1
,
,}

1.
Anshan Iron & Steel Co., Ltd., Anshan 114009, Liaoning, China
2.
State Key Laboratory of Metallic Materials for Marine Equipment and Applications, Anshan 114021, Liaoning, China
3.
Shenyang University of Technology, Shengyang 110023, Liaoning, China

More Information

Received Date: 2025-08-06
Accepted Date: 2025-09-09
Rev Recd Date: 2025-08-25

Available Online: 2025-12-31

Publish Date: 2025-12-31

Abstract

Abstract

In this research, the effects of relaxation times varying from 0 s to 75 s after rolling on the microstructure and mechanical properties of thin-gauge 450 MPa grade high-strength steel were studied. The room temperature tensile performance, CVN impact energy at -20 ℃ and DWTT drop hammer test at -15 ℃were performed. The microstructure and precipitates evolution of 450 MPa grade obtained with different relaxation times were observed by using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results showed that with the prolongation of relaxation time, the grain size and ratio of PF increased, the volume fraction of Nb/Ti-rich nano carbonitride precipitation firstly increased and decreased, the yield, tensile strength, fracture elongation, -20 ℃ CVN impact energy and -15 ℃ DWTT properties also showed similar trend. While the yield ratio decreased firstly, and then increased. When the relaxation time was 60 s, the higher strength and toughness and the lower yield ration were achieved, those could meet the technical requirements for steel used in engineering structures.
- precipitates,
- high-strength steel,
- YS-UTS ratio,
- relaxation,
- grain size

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References(17)

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