Evolution of non-metallic inclusions in EAF-LF-VD-CC process of GCr15 bearing steel
WANG Kang1, LIU Jian-hui2, YANG Shu-feng1, LI Jing-she1
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. State Key Laboratory of Advanced Steel Processes and Products, Central Iron and Steel Research Institute, Beijing 100081, China
Abstract:To study the evolution of non-metallic inclusions in GCr15 bearing steel.The GCr15 bearing steel produced by EAF-LF-VD-CC process was sampled in various stages in a steel factory. The evolution behavior of inclusions in various processes was systematically analyzed by scanning electron microscopy (SEM-EDS) and ASPEX inclusion quick analysis equipment, which can scan large areas. The result indicates that the main types of inclusions in the refining process of GCr15 bearing steel are MgO-Al2O3-CaO compound inclusions, MnS inclusions and a small amount of SiO2-Al2O3 inclusions, more than 90% of the inclusions distribute in 1-8 μm. With the progress of refining, the number of inclusions decreases gradually, and the number and total area of inclusions decrease to the lowest at the VD soft blowing process. During the refining, the inclusions were gradually transferred to the areas with elevated MgO and CaO content from the initial high Al2O3 (w([Al2O3])>80%) region. After the vacuum condition breaking, the MgO (w([MgO])>20%) and CaO (w([CaO])>30%) reached the highest. It then moves to the area where the Al2O3 content is elevated, and finally stays in the high Al2O3 (w([Al2O3])>65%) region in the tundish. The main Ds inclusions in steel are MgO-Al2O3-CaO composite inclusions. The formation and removal of Ds inclusions are random. The VD process has a strong removal effect on Ds inclusions.
王康, 刘剑辉, 杨树峰, 李京社. GCr15轴承钢EAF-LF-VD-CC流程非金属夹杂物的演变[J]. 钢铁, 2020, 55(2): 48-55.
WANG Kang, LIU Jian-hui, YANG Shu-feng, LI Jing-she. Evolution of non-metallic inclusions in EAF-LF-VD-CC process of GCr15 bearing steel. Iron and Steel, 2020, 55(2): 48-55.
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