Open AccessElectromagnetic stirring in billet CCM molds and continuously casted billet quality
Author(s) -
С. И. Шахов,
К. Н. Вдовин
Publication year - 2019
Publication title -
černaâ metallurgiâ. bûlletenʹ naučno-tehničeskoj i èkonomičeskoj informacii/černaâ metallurgiâ. bûlletenʹ naučno-tehničeskoj informacii
Language(s) - English
Resource type - Journals
eISSN - 2619-0753
pISSN - 0135-5910
DOI - 10.32339/0135-5910-2019-8-955-961
Subject(s) - mold , mechanical engineering , materials science , liquid metal , continuous casting , casting , metallurgy , engineering , composite material
Electromagnetic stirring (EMS) is one of methods to improve the quality of continuously casted billet. Under EMS impact nonmetallic inclusions are removed out of the solidification area and move to the center of meniscus of liquid metal. Besides, high speeds of convection flows in the liquid metal avoid the remaining of gases at the crystallization border and decrease therefore the number of gas bubbles under metal shell. This mechanism of EMS action in a mold results in decreasing of gas bubbles under the metal shell and impurities in continuously casted billet. Operation of a billet CCM was studied at Moldavsky steel-works, where an EMS stator was imbedded into the mold. Influence of EMS on the quality of continuously casted billet was studied. The work was accomplished in several stages. First, the EMS system with a test mold with electromagnetic stirrer was studied for casting of 135×135 mm billets and 800 mm long, next 125×125 mm billet and 1000 mm long and then 125×125 mm billet and 800 mm long. Main comparative parameters of used EMS systems in the mold presented in the article. All the molds-EMS systems were designed based on existing regular molds so that they could be installed at the CCM without changing the existing oscillation frame and water input and output piping. As a result of templates metal science studies cut out of test and regular metal, influence of EMS in the mold on the billet macro structure was revealed, comparing with a standard strand. The following phenomena were studied: decrease of average degree of cracks and liquation strips along the billet section, of cracks in the billet axis zone, central pore volume and border point contaminations; increase of axis liquation degree (but liquation became more distributed), decrease of carbon axis liquation coefficient in high carbon steels. The average growth values of equiaxed crystal zone at the templates of test heats with EMS amounted for 55% at high carbon steels comparing with regular billet templates, at the middle carbon steels – 48%, at the low carbon steels – 92%. The elaborated EMS system in the mold allows improving considerably the quality of continuously casted billets.