Internal quality control of 160 mm×160 mm square billet of 20CrMnTi steel with EMS
KANG Ji-bai1, WANG Wei-ling1, LUO Teng-fei1, LUO Sen1, ZHU Miao-yong1,2
1. School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China; 2. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, Liaoning, China
Abstract：In order to improve the severe internal quality problems in continuously cast 160 mm×160 mm billets of 20CrMnTi, industrial tests to optimize synergistically processing parameters of mold electromagnetic stirring(M-EMS) and final electromagnetic stirring(F-EMS) were carried out. The effects of technical parameters on the internal quality of 20CrMnTi billets were analyzed in detail through the chemical etching for the macrostructure and via measurements for the carbon contents. Besides,an infrared thermal image instrument was used to test the billet surface temperature,and ANSYS software was subsequently utilized to calculate the temperature variation during the solidification of the billet. Accordingly,the thickness of the liquid pool at F-EMS was obtained. The results show that the initial locations of columnar-to-equiaxed transition(CET) zone at the inner arc and outer arc sides are fixed around 42 and 28 mm,respectively,and they have only a little change within the range of M-EMS current intensity from 240 to 260 A. There exists negative segregation of carbon at 10 mm below the billet surface. However,carbon enriches in front of the CET zone and appears to be positive and negative segregation alternately in the solidification center. The negative segregation of carbon in the vicinity of the solidification center is positively correlated with the stirring intensity of M-EMS and F-EMS. According to the experimental results,the optimal parameters of M-EMS and F-EMS are 250 A/4.0 Hz and 300 A/7.0 Hz,respectively. Additionally,the liquid pool’s thicknesses vary from 66.2 mm at the entrance of F-EMS stirrer to 60.6 mm at the outlet of F-EMS stirrer and the corresponding solidification ratio ranges from 86.6% to 88.7%,which manifests that the current F-EMS implemented position is proposed.
康吉柏, 王卫领, 罗腾飞, 罗森, 朱苗勇. 20CrMnTi钢160 mm×160 mm方坯内部质量控制[J]. 钢铁, 2021, 56(2): 82-92.
KANG Ji-bai, WANG Wei-ling, LUO Teng-fei, LUO Sen, ZHU Miao-yong. Internal quality control of 160 mm×160 mm square billet of 20CrMnTi steel with EMS[J]. Iron and Steel, 2021, 56(2): 82-92.
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2021, Vol. 56 
