VOD is a refining device for smelting stainless steel, ultra-low carbon steel and alloy under vacuum. In the refining process, the main effects on the furnace lining refractory are:
Selection of refractories for VOD vacuum furnace
- Vacuum and high temperature. When VOD furnace is smelted under vacuum, the vacuum degree in the furnace is 66.66 ~ 133.32pa, and the temperature in the furnace can reach more than 1700 ℃.
- Alkalinity change. When the alkalinity is 0.5 ~ 4, the alkalinity of slag changes greatly and has strong erosion on furnace lining materials. In the initial stage of smelting, low alkalinity slag is required. In the later stage, in order to preserve chromium and remove sulfur, reducing high alkalinity slag is required, and the alkalinity can reach more than 4.
- Liquid steel flows and circulates quickly. Due to the simultaneous injection of argon and oxygen, the gas stirring effect is strong, and the molten steel and slag have great scouring and wear on the solid materials of the furnace.
- Intense thermal shock. VOD furnace is an intermittent operation equipment, which is used 2 ~ 3 times a day, so the temperature changes greatly, the temperature of refractory changes violently, and the impact of thermal shock is great.
- High temperature for a long time. Due to the long smelting time, which is generally about 1 hour, the furnace lining material will be subjected to vacuum and high temperature for a long time.
Requirements for refractory materials of VOD furnace
According to the process conditions of VOD furnace, the refractory shall have the following characteristics:
(1) Good stability under high temperature and vacuum conditions;
(2) Under high temperature operation conditions, the refractory shall have slag penetration resistance and erosion resistance;
(3) It shall have good thermal shock resistance.