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. Xichang Steel and Vanadium Limited Company, Pangang Group, Xichang 615000, Sichuan, China
Abstract：To further improve the properties of dual phase steels, 1 500 MPa grade Nb-Ti microalloyed high elongation cold-rolled dual phase steel was developed in the laboratory by reasonable chemical composition design, and the influence of annealing temperature and over-aging temperature on the microstructure and mechanical properties of dual phase steel was systematically studied by means of continuous annealing simulator and scanning electron microscope. The results show that, the tensile strength increases with the increase of annealing temperature, reaching 1 650 MPa at 840 ℃. Tempered martensite begins to appear in the structure as the temperature continues to increase, and the tensile strength decreases. As the over-aging temperature increases, the proportion of tempered martensite in the structure decreases, and the proportion of quenched martensite increases, as the temperature continues to rise, bainite is also formed, so the elongation continue to increase overall. The tensile strength can reach 1 520 MPa at 380 ℃, and the elongation rate can reach 8.3%, achieving the best mechanical properties.
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KONG Z, ZHANG J, LI H, et al. Effects of continuous annealing process parameters on the microstructure and mechanical properties of dual phase steel[J]. Steel Research International, 2018, 89(8): 1800034.
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CAI M, CHEN L, FANG K, et al. The effects of a ferritic or martensitic matrix on the tensile behavior of a nano-precipitation strengthened ultra-low carbon Ti-Mo-Nb steel[J]. Materials Science and Engineering A,2021,801:1404.
2022, Vol. 32 
