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| Analysis and control of the forming cause of slag inclusion on the surface of Q345B casting slab |
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Received:August 07, 2017
Revised:August 14, 2017
Accepted:August 14, 2017
Published Online:March 29, 2018
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| DOI： |
| KeyWord:Casting defects on the surface of slag inclusion; Q345B steel; negative slip time; fractional melting caused |
| Author | Institution |
| zhanzhonghua |
Faculty of Metallurgical and Energy Engineering，Kunming University of Science and Technology;National Research Center of Continuous Casting Technology, Central Iron and Steel Research Institute |
| qiushengtao |
National Research Center of Continuous Casting Technology, Central Iron and Steel Research Institute |
| shizhe |
Faculty of Metallurgical and Energy Engineering，Kunming University of Science and Technology |
| xulijun |
National Research Center of Continuous Casting Technology, Central Iron and Steel Research Institute |
| yinshubiao |
Faculty of Metallurgical and Energy Engineering，Kunming University of Science and Technology |
| laichaobin |
School of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology |
| malijun |
Technical Center of Tianjin Iron and Steel Group Company Limited |
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| Abstract: |
| Analysis and control of the forming cause of slag inclusion on the surface of Q345B casting slab
ZHAN Zhong hua1，2，QIU Sheng tao2，SHI Zhe1 XU Li jun2 YIN Shu biao1，LAI Chao bin3,MA Li jun4
(1.Faculty of Metallurgical and Energy Engineering，Kunming University of Science and Technology，Kunming 650093，China；2. National Research Center of Continuous Casting Technology, Central Iron and Steel Research Institute, Beijing 100081, China;3. School of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000,China；4. Technical Center of Tianjin Iron and Steel Group Company Limited，Tianjin 300301，China))
Abstract: This paper describes the macroscopic morphology of the slag pit on the surface of microalloyed steel Q345B. The morphology and composition of the defects were analyzed by SEM and Energy Spectrometer. The results show that the slag pit in the casting slab was mainly iron oxide scale and contains a small amount of protection residue. Analyzes the reasons for the formation of slab surface slag defects basically has the following 4 aspects: slag entrapment caused by surface fluctuation due to the unreasonable design of the submerged nozzle、wrapped slag caused by the hit on meniscus in the mold、the fractional melting caused by the uneven composition of the mold fluxes and the long time of the mold vibration negative slip. Thus the following optimization measure are proposed: Firstly, the structure of the submerged nozzle is optimized by reducing the angle of the side hole form 25°to 18°. Secondly, the flow vectors in the mold is improved, the argon flow rates between the plates has been reduced from 5 L/min to less than 3 L/min and the insertion depth of SEN is controlled between 90 and 130mm. Thirdly optimize the composition and performance of mold slag, the melting point of the protection residue has increased from 1050℃ to 1150℃, the basicity is greater than 1 and the viscosity is between 0.12Pa?s and 0.2Pa?s. Thirdly, the negative slip time is reduced from 0.207s to 0.165s by adjusting the vibration coefficient of the mold . The results of 22 field tests show that the surface crack of the plate caused by slag pit was controlled below 1%, and the surface quality control of the casting slab and plate is realized. |
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