Determination and analysis of SH-CCT curve of Q345FRE fire-resistant steel

doi:10.13251/j.issn.0254-6051.2022.10.014

Abstract

Abstract: Welding thermal simulation of Q345FRE fire-resistant steel was carried out by using Gleeble-3500 testing machine. And the phase transition temperature of welding HAZ in the Q345FRE steel under different t_8/5 conditions was measured by means of expansion method, lever method, metallographic analysis and hardness, then SH-CCT curve of the Q345FRE steel was drawn, and the microstructure change of welding HAZ in the Q345FRE steel under different t_8/5conditions was studied. The results show that the microstructure of HAZ in the Q345FRE steel is bainite when t_8/5 is in the range of 3-80 s; when t_8/5 is in the range of 80-300 s, the microstructure is bainite, ferrite and pearlite; when t_8/5 is in the range of 300-600 s, the microstructure is ferrite and pearlite. As t_8/₅ increases, the hardness of HAZ in the Q345FRE steel decreases. In order to maintain the microstructure stability, it is suggested that the proper welding line energy of the Q345FRE fire-resistant steel should be selected in the range of 15-150 kJ/cm.

Key words: Q345FRE fire-resistant steel, SH-CCT curve, microstructure, hardness

CLC Number:

TG142.7

Liu Pan, Wang Honghong, Yan Wenze, Peng Siyuan. Determination and analysis of SH-CCT curve of Q345FRE fire-resistant steel[J]. Heat Treatment of Metals, 2022, 47(10): 88-93.

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