Precipitation mechanism and improvement of primary carbide in Nb-H13 steel
CAO Xiao-jun1, LI Ming-lin1, HUANG Yu2, CHENG Guo-guang2,DAI Wei-xing2, XIE You3
1. Steelmaking Department, Xining Special Steel Co., Ltd., Xining 810005, Qinghai, China; 2. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China; 3. Technology Center, Zenith Steel Co., Ltd., Changzhou 213011, Jiangsu, China
Abstract:In order to obtain the appropriate Nb content in the Nb microalloyed H13 steel, the primary carbide in H13 steel was taken as the research object, and the H13 steels melted in the laboratory with different Nb mass fraction addition were analyzed to study the precipitation mechanism of the primary carbide. The results showed that when the Nb mass fraction in H13 steel is lower than 0.03%, the primary carbide in the H13 steel was mainly the V-rich phase. When the Nb mass fraction in H13 steel reached 0.05%, the primary carbides were mainly the V-rich phase and the Nb-rich phase. Therefore, the Nb mass fraction in the Nb microalloyed H13 steel should be lower than 0.03%. The Nb mass fraction had a significant effect on the precipitation sequence of the primary carbide in the FCC phase. As the Nb mass fraction increased, the precipitation sequence of carbide in FCC phase changes from V-rich phase to Nb-rich phase, and the thermal stability of the Nb-rich phase was much higher than that of the V-rich phase. The theoretical calculation results were basically consistent with the experimental observations, and the industrial test results also demonstrated the results of this study.
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