Corundum refractory bricks used in RH furnaces

A RH vacuum degasser was initially used as a degasser and the refractory lining was mainly built with high alumina brick and fire clay brick. Now, the functi refractories are used.
With the increase in productionon of RH furnaces has been extended to the oxygen blowing and dusting. Since the conditions become more demanding, advanced of advanced special steel, methods that can increase the circulation and the amount of gas blown are promoted for stable production and high-speed processing of ultra-low carbon steel. The increase of circulation increases the wear of the lining; the cold air causes the high temperature spalling; the intake volume of ladle slags can exacerbate the structural spalling and erosion. All these intensify the damage of lining materials. Now, the lining of RH/RH-OB furnaces is mainly built with direct bonded corundum bricks and the oxygen blowing mouth is semi-bonded or rebounded corundum brick and magnesia carbon brick.
The refractory materials used in the top and the upper slot of RH devices are no in direct contact with molten steel and slags, so they are not damaged co severely compared to the lower parts. The middle parts are easy to be damaged since they are in direct contact with molten steel and slags. The lower slot including the immersion tubes are the high corrosive areas and the weak point of RH furnaces, so it often determines the service life of RH furnaces. The lining of the lower slot is always built with direct bonded corundum bricks. The circulation pipe is the most seriously damaged part in the lower parts of RH furnaces, because the lining structure limits its thickness and bricks with complex shapes should be heated twice. In addition, in RH-OB furnaces, OB also has great effect on the refractory materials. When the spray gun is set on the upper parts, refractory materials are subjected to the corrosion by oxygen, iron oxides in molten steel and high temperature gases, so, MgO-Cr2O3 bricks with a high content of Cr2O3 should be used.
Corundum bricks including direct bonded, rebounded and semi-rebounded corundum bricks have good resistance to low basicity slags, so they are widely used in refining furnace linings.