Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 1

• Дата: 2023
• Автори: Писарський, Сергій, Смірнов, Олексій
• Формат: Стаття
• Мова: Англійська
• Опубліковано: Physico-technological Institute of Metals and Alloys 2023
• Теми: сортова МБЛЗ; ромбічнiость; применіскова область; флуктуації рівня; нерівномірність тепловідведення і затвердіння; умови контакту в кристалізаторі; тривимірна деформація
• Онлайн доступ: https://www.metalsandcasting.com/index.php/mcu/article/view/59
• Назва журналу: Metal and Casting of Ukraine

The rhomboidity of the profile being shape defect of continuously cast billets despite advanced technology of their production and improvement of billet continuous casting machines (CCM) design development continues to occupy a significant part among other typical defects. Modern concepts about the nature of this defect remain incomplete and for a number of points – as unconfirmed assumptions. One of the most noticeable “white spots“ among them is the vexed question about the reason for increased addiction of mediumcarbon steel to rhomboidity. Research carried out by the authors aimed at circumstantiation and development existing concepts about the regularities and mechanisms of the rhomboidity formation as a multilevel and multifactorial process. The rhomboidity initiation occurs in the mould meniscus region due to non-uniform heat removal from the billet along the profile perimeter. The reason for the non-uniform heat removal can be considered the local contact conditions between billet and mould that differ along the perimeter. The trigger of the square profile deformation process occurs when the heat removal intensity decreases even in one of its corners. According to the authors the metal level fluctuations in the mould caused by the instability of the turbulent jet from tundish cannot be considered as a dominant and independent factor in the rhomboidity initiation. Specific level fluctuations often observed in the “rhombic“ strands of CCM are primarily due to the dynamic interaction of billet with mould. One of the main reasons for the differing billet with mould contact conditions was offered to consider the billet  spatial (three-dimensional) deformation within the CCM casting arc that can be investigated as a multifactorial ”Mould – Billet – Secondry Cooling Zone” (M-B-SCZ) system. Proposed approach allows integration to improved concept both the provisions the objectivity of which has been proven in the course of previous research and the data known from practice regarding the influence of many technological, technical and other factors on the rhomboidity. This approach also makes it possible to more objectively and deeply understand the regularities and mechanisms of the rhomboidity formation as a multilevel process. This is a prerequisite for improving the billet quality, developing new technological solutions and optimizing preventive measures aimed at billet rhomboidity reducing.