Effect of Cr and isothermal holding temperature on microstructure and properties of complex phase steel with high formability (CH steel)
Xiao-hong Chu1,2, Peng-fei Gao1,2, Wei-jian Chen1,2, Feng Li1,2, Tao Kang1,2, Yan Zhao1,2, Xian-dong Yin3, Zheng-zhi Zhao1,2
1 Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China 2 Beijing Laboratory for Modern Transportation Advanced Metal Materials and Processing Technology, University of Science and Technology Beijing, Beijing 100083, China 3 Technical Center, Shougang Jingtang United Iron and Steel Co., Ltd., Tangshan 063200, Hebei, China
Effect of Cr and isothermal holding temperature on microstructure and properties of complex phase steel with high formability (CH steel)
Xiao-hong Chu1,2, Peng-fei Gao1,2, Wei-jian Chen1,2, Feng Li1,2, Tao Kang1,2, Yan Zhao1,2, Xian-dong Yin3, Zheng-zhi Zhao1,2
1 Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China 2 Beijing Laboratory for Modern Transportation Advanced Metal Materials and Processing Technology, University of Science and Technology Beijing, Beijing 100083, China 3 Technical Center, Shougang Jingtang United Iron and Steel Co., Ltd., Tangshan 063200, Hebei, China
摘要 The effects of Cr contents (0.3 and 1.0 wt.%) and isothermal holding temperatures (400, 440, and 480 ºC) on the microstructure evolution and properties of complex phase steel with high formability (CH steel) were investigated using dilatometry, scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction. The results show that the microstructures of CH steel with 0.3 wt.% Cr are ferrite, granular bainite, martensite, and retained austenite, while no ferrite is observed in the microstructure of CH steel with 1.0 wt.% Cr in the same process. Cr promotes the precipitation of (Nb, Ti)C in the high-temperature austenite region through theoretical calculations and TEM observations. Cr retards the bainite transformation and refines the grain size of CH steel. Furthermore, as isothermal holding temperature increases from 400 to 480 ºC, the bainite and retained austenite fractions of two CH steels decrease, while the martensite fraction increases in the steels after final quenching. Consequently, the strength has an increasing tendency and the total elongation has a decreasing tendency with increasing isothermal temperature.
Abstract：The effects of Cr contents (0.3 and 1.0 wt.%) and isothermal holding temperatures (400, 440, and 480 oC) on the microstructure evolution and properties of complex phase steel with high formability (CH steel) were investigated using dilatometry, scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction. The results show that the microstructures of CH steel with 0.3 wt.% Cr are ferrite, granular bainite, martensite, and retained austenite, while no ferrite is observed in the microstructure of CH steel with 1.0 wt.% Cr in the same process. Cr promotes the precipitation of (Nb, Ti)C in the high-temperature austenite region through theoretical calculations and TEM observations. Cr retards the bainite transformation and refines the grain size of CH steel. Furthermore, as isothermal holding temperature increases from 400 to 480 oC, the bainite and retained austenite fractions of two CH steels decrease, while the martensite fraction increases in the steels after final quenching. Consequently, the strength has an increasing tendency and the total elongation has a decreasing tendency with increasing isothermal temperature.
Xiao-hong Chu,Peng-fei Gao,Wei-jian Chen, et al. Effect of Cr and isothermal holding temperature on microstructure and properties of complex phase steel with high formability (CH steel)[J]. Journal of Iron and Steel Research International, 2023, 30(02): 328-337.
2023, Vol. 30 
