Title: The measurement of SH-CCT curve and analysis on microstructure and performance of heat-affected zone of Q690 high-strength bridge steel

Authors: Xuming Wang; Aimin Zhao; Supeng Liu; Zhiyi Bao

Addresses: Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing, 100083, China; China Railway Fifth Survey and Design Institute Group Co. Ltd., Beijing, 102600, China ' Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing, 100083, China ' Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing, 100083, China ' Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing, 100083, China

Abstract: The heat-affected zone continuous cooling transition curve (SH-CCT) of the experimental steel is drawn by using the Gleeble-3500 thermal simulation testing machine. The influences of different cooling rates and peak temperatures on the microstructure and mechanical properties of HAZ were studied. The results show as the cooling rate increases, the experimental steel undergoes LB + GB and LM + LB + GB phase transformations successively, and the micro-hardness gradually increases. When the heat input is 20kJ/cm, the microstructure of inter-critical heat-affected zone (ICHAZ) is F + B, the microstructure of fine grain heat-affected zone (FGHAZ) and the coarse grain heat-affected zone (CGHAZ) is LM + LB + GB. As the peak temperature increases, the micro-hardness first increases and then decreases, the -40°C impact absorbing energy gradually decreases. This conclusion can provide a reference for further study on the microstructure and mechanical properties of HAZ of Q690 bridge steel.

Keywords: Q690 bridge steel; SH-CCT curve; peak temperatures; microstructure; mechanical properties.

DOI: 10.1504/IJMMP.2021.121637

International Journal of Microstructure and Materials Properties, 2021 Vol.15 No.5/6, pp.356 - 369

Received: 31 May 2021
Accepted: 13 Oct 2021
Published online: 22 Mar 2022 *

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