1. Manufacture Division,Shougang Jingtang Iron and Steel Co., Ltd., Tangshan 063200, Hebei, China; 2. School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing, Beijing 100083, China; 3. Steelmaking Department,Shougang Jingtang Iron and Steel Co., Ltd., Tangshan 063200, Hebei, China; 4. Research Institute of Technology, Shougang Group Co., Ltd., Beijing 100043, China
Abstract：Based on the comparative analysis of inclusions control of pipeline steel at home and abroad, the objective of inclusion control of pipeline steel is proposed to be solid inclusions of Al2O3-CaS system, and the influence and quantitative relationship of liquid steel composition on the formation of such inclusions are systematically studied. The results show that there are two formation mechanisms of Al2O3-CaS inclusions after calcium treatment. The precise control of different types of inclusions can be achieved by adjusting the composition of Ca, S, T[O]. With the increase of Ca/T[O] ratio in steel, the content of Al2O3in inclusions decreases significantly. When the Ca/T[O] ratio is less than 0.5, the inclusions in steel are mainly composed of Al2O3. When the Ca/T[O] ratio is between 0.5 and 1.5, the inclusions are mainly composed of Al2O3-CaS. When the Ca/T[O] ratio is greater than 1.5, the inclusions are mainly composed of CaO-CaS. After the process optimization, the unqualified rate of inclusions in high grade pipeline steel is reduced from 3.12% to 1.54%, and the proportion of inclusions in all high-level pipeline steel less than 1.5 level is increased from 90% to 95.4%.
WANG X H, LI X G, LI Q, et al. Control of stringer shaped non-metallic inclusions of CaO-Al2O3 system in API X80 linepipe steel plates[J]. Steel Research International, 2014, 85(2): 155.
YANG G W, WANG X H, HUANG F X, et al. Influence of Calcium addition on inclusions in LCAK steel with ultralow sulfur content[J]. Metall. Mater. Trans. B, 2015, 46(1): 145.
[7]
唐德池,张宏艳,吉利鹏,等. 钙处理车轮钢洁净度[J].钢铁,2018,53(4): 37.
[8]
Holappa L,Hamalainen M,Liukkonen M, et al. Thermodynamic examination of inclusion modification and precipitation from calcium treatment to solidified steel[J]. Ironmaking and Steelmaking, 2003, 30(2): 111.
2020, Vol. 30 
