Вплив режимів роботи електромагнітного перемішувача на структуру сортової заготовки в умовах сучасних мікрозаводів

• Дата: 2023
• Автори: Верзілов, Олексій, Смірнов, Олексій, Семенко, Анастасія
• Формат: Стаття
• Мова: Українська
• Опубліковано: Physico-technological Institute of Metals and Alloys 2023
• Теми: металургійний мікро-завод; електромагнітний перемішувач; кристалізатор; безперервне розливання; сортова заготовка
• Онлайн доступ: https://www.metalsandcasting.com/index.php/mcu/article/view/27
• Назва журналу: Metal and Casting of Ukraine

Improving the quality of the billet can be achieved by applying external influences on the hardening metal, in particular, when a traveling magnetic field is applied to the liquid phase of the ingot. Electromagnetic mixing can be carried out on different parts of the billet during its formation on the Continuous Casting Machine (CCM), that is, in the mold, in the secondary cooling zone and in the lower part of the liquid well. Electromagnetic mixing in the mold of CCM is one of the most effective methods of physical action on liquid metal in order to form a high-quality surface and internal structure of a continuous cast ingot. This is due to the fact that the primary crust of the billet that hardens has a small thickness and its thermal resistance to heat transfer to the mold wall is minimal. At the same time, the creation of forced mixing contributes to the movement of a hotter metal to the hardening front, that is, heat and mass exchange processes in this area are intensified. Experimental studies of the effect of electromagnetic stirrer (EMS) operating modes on the dendritic structure of a 180 mm square billet were carried out on a six-thread radial CCM. The macrostructure was studied on the metal of billet cast on the first and sixth streams of the CCM at current values in the EMS windings of 217 A and 500 A, respectively. For analysis, transverse templates (washers) were selected, from which a transverse strip with a width of 25 mm was cut out. After grinding, polishing, and examining the surface of the templates, they were etched onto the dendritic structure with Sted reagent in order to study the effect of the intensity of electromagnetic mixing on the structure, crystallization rate, and distribution of non-metallic inclusions. Experimental studies have shown that electromagnetic mixing of metal in the mold of CCM significantly enhances heat and mass transfer processes and has a significant impact on the formation of the billet structure. With an increase in the intensity of electromagnetic mixing, the length of the zone of columnar dendrites from the small radius side decreases by 20 mm, and the zone of equiaxal crystals expands accordingly. It was found that the most characteristic non-metallic inclusions in the studied billets are oxides and sulfides. It should be noted that an increase in the current value in the EMS winding leads to the elimination of axial looseness and a decrease in the total hardening time of the billet by 7–8 %.