Regulation effect of post-rolling quenching and tempering treatment on element segregation and banded microstructure in hot-rolled Q345R steel

YANG Yan; WANG Hemu; GAO Qing; PENG Fei; ZHANG Kaiming; YUAN Wuhua

doi:10.7513/j.issn.1004-7638.2025.06.022

Volume 46 Issue 6

Dec. 2025

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YANG Yan, WANG Hemu, GAO Qing, PENG Fei, ZHANG Kaiming, YUAN Wuhua. Regulation effect of post-rolling quenching and tempering treatment on element segregation and banded microstructure in hot-rolled Q345R steel[J]. IRON STEEL VANADIUM TITANIUM, 2025, 46(6): 179-185. doi: 10.7513/j.issn.1004-7638.2025.06.022

Citation:

YANG Yan, WANG Hemu, GAO Qing, PENG Fei, ZHANG Kaiming, YUAN Wuhua. Regulation effect of post-rolling quenching and tempering treatment on element segregation and banded microstructure in hot-rolled Q345R steel[J]. IRON STEEL VANADIUM TITANIUM, 2025, 46(6): 179-185. doi: 10.7513/j.issn.1004-7638.2025.06.022

Citation:

YANG Yan, WANG Hemu, GAO Qing, PENG Fei, ZHANG Kaiming, YUAN Wuhua. Regulation effect of post-rolling quenching and tempering treatment on element segregation and banded microstructure in hot-rolled Q345R steel[J]. IRON STEEL VANADIUM TITANIUM, 2025, 46(6): 179-185. doi: 10.7513/j.issn.1004-7638.2025.06.022

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Regulation effect of post-rolling quenching and tempering treatment on element segregation and banded microstructure in hot-rolled Q345R steel

doi: 10.7513/j.issn.1004-7638.2025.06.022

1.
Hunan Valin Xiangtan Iron and Steel Co., Ltd., Xiangtan 411101, Hunan, China
2.
School of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, China

More Information

Received Date: 2025-05-09
Accepted Date: 2025-06-19
Rev Recd Date: 2025-06-11

Available Online: 2025-12-31

Publish Date: 2025-12-31

Abstract

Abstract

The regulation effect and mechanism of quenching and tempering treatment after rolling (890 ℃ quenching + 710 ℃ tempering) on element segregation and the resultant banded microstructure in hot-rolled Q345R steel were thoroughly investigated. The results show that the microstructure of the hot-rolled Q345R steel consists of recrystallized ferrite and pearlite. The pearlite is distributed in bands and granular pearlite presents at the ferrite grain boundaries and within ferrite grain. The matrix microstructure of Q345R steel prepared by quenching and tempering treatment is tempered martensite containing a small amount of recrystallized martensite, with dense cementite precipitation bands observed in C- and Mn-rich regions of the tempered martensite. Critically, significant C and Mn segregation exists in both hot-rolled and quenched & tempered Q345R steel, and the banded microstructure (pearlite bands or cementite precipitation bands) highly coincides with the segregation bands. Although quenching and tempering after rolling does not eliminate the solidification-inherited element segregation, it effectively regulates the formation mode and characteristics of the banded structure by disrupting the high dependence of solid-state phase transformation on the original elemental distribution via martensitic transformation, reducing the banding severity from grade 5B to 3B. Concurrently, it reduces the strength difference between soft and hard phases from 206.76 MPa to 119.48 MPa, thereby ameliorating the mechanical property inhomogeneity induced by the banded microstructure.
- Q345R steel,
- banded microstructure,
- quenching and tempering treatment,
- element segregation,
- tempered martensite

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References(20)

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