Determination of SH-CCT Curve and Microstructure and Properties of Heat-Affected Zone in Q420qENH Steel Composite Steel Plate Substrates

FU Yanqing; FENG Fei; LI Jie; ZENG Zhouyu; ZHANG Di; MA Dezhi; WU Bin

doi:10.3724/j.gyjzG25061101

Volume 55 Issue 9

Sep. 2025

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FU Yanqing, FENG Fei, LI Jie, ZENG Zhouyu, ZHANG Di, MA Dezhi, WU Bin. Determination of SH-CCT Curve and Microstructure and Properties of Heat-Affected Zone in Q420qENH Steel Composite Steel Plate Substrates[J]. INDUSTRIAL CONSTRUCTION, 2025, 55(9): 1-7. doi: 10.3724/j.gyjzG25061101

Citation:

FU Yanqing, FENG Fei, LI Jie, ZENG Zhouyu, ZHANG Di, MA Dezhi, WU Bin. Determination of SH-CCT Curve and Microstructure and Properties of Heat-Affected Zone in Q420qENH Steel Composite Steel Plate Substrates[J]. INDUSTRIAL CONSTRUCTION, 2025, 55(9): 1-7. doi: 10.3724/j.gyjzG25061101

Citation:

FU Yanqing, FENG Fei, LI Jie, ZENG Zhouyu, ZHANG Di, MA Dezhi, WU Bin. Determination of SH-CCT Curve and Microstructure and Properties of Heat-Affected Zone in Q420qENH Steel Composite Steel Plate Substrates[J]. INDUSTRIAL CONSTRUCTION, 2025, 55(9): 1-7. doi: 10.3724/j.gyjzG25061101

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Determination of SH-CCT Curve and Microstructure and Properties of Heat-Affected Zone in Q420qENH Steel Composite Steel Plate Substrates

doi: 10.3724/j.gyjzG25061101

1. Central Research Institute of Building and Construction Co., Ltd, MCC Group, Beijing 100088, China;
2. School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing, Beijing 100083, China;
3. Nanjing Iron & Steel Company Limited, Nanjing 210035, China;
4. Sichuan Kangxin Expressway Co., Ltd., Ganzi 626099, China

Received Date: 2025-06-11
Available Online: 2025-11-05

Abstract

Abstract

Using the MMS-200 thermal simulation testing machine， the microstructure of the heat-affected zone （HAZ） of the Q420qENH steel matrix in Q420qENH composite steel plates was determined under different t_8/5 cooling speeds. Based on microstructural observation and hardness analysis， the microstructural and hardness changes of the weld heat-affected zone （HAZ） of Q420qENH steel were determined at different t_8/5 cooling speeds， and the continuous cooling transformation （CCT） curves of the weld HAZ were plotted. The results showed that when the t_8/5 cooling rate was between 1 ℃/s and 10 ℃/s， the transformation products of the test steel were F+GB， and there were no significant changes in grain size and hardness as the cooling rate increased； When the t_8/5 cooling rate was between 15 ℃/s and 45 ℃/s， the transformation products of the test steel were ferrite and lower bainite， with grain size decreasing and hardness increasing. Among these， Q420qENH steel exhibited the highest grain size and hardness at a cooling rate of 15 ℃/s. To ensure that the welded joint meets performance requirements， when welding Q420qENH steel base material， the cooling rate should be controlled between 1 ℃/s and 45 ℃/s， with corresponding weld heat input controlled within a range of 7.2 kJ/cm to 48.0 kJ/cm.
- Q420qENH weathering steel,
- SH-CCT curve,
- microstructure,
- welding line energy

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References(12)

References

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