Advantages of ladle air bricks

1. Effect of thermal stress

The refractory materials on the working surface of ladle air bricks, especially the refractory materials around the outlet, are in direct contact with high-temperature molten steel, and are affected by high-temperature molten steel and the continuously flowing cold air flow, resulting in a large temperature gradient. Due to repeated use, the ladle air bricks are subjected to large rapid cooling and heating effects, especially the thermal stress near the outlet is greater, and cracks are prone to occur.

2. Effect of mechanical wear

During the steel-making process, the high-speed molten steel and the scouring of the bottom of the steel tank accelerate the corrosion of the ladle air bricks; someone has studied the corrosion of the ladle air bricks through hydraulic model tests and found that: when the low-speed flowing air flow is injected into the liquid phase molten pool, the air flow rebounds and hits the front edge of the ladle air bricks, giving a certain impact force to the refractory materials around the outlet. When the gas flow rate is further increased, the reverse pulse frequency decreases, but the reverse impact intensity increases further; in addition, when the argon blowing enters the normal eruption state, the intense bubbles form a gas eruption beam, which strengthens the stirring at the bottom of the steel tank, intensifies the liquid phase movement at the bottom of the steel tank, and the two-phase vortex causes the ladle air bricks to be subjected to intense shear and impact stress. When the ladle air bricks are higher than the seat bricks, they are particularly sheared and scoured by this vortex, and the part higher than the seat bricks is generally washed away after one use; in addition, if the valve is closed quickly after the refining is completed, the reverse impact of the molten steel will also accelerate the damage of the ladle air bricks.

3. Chemical erosion effect

The working surface of the ladle air bricks has a long contact time with the slag and molten steel. During the entire ladle service, the slag continuously moisturizes and penetrates into the bricks.

4. Effect of mechanical stress

The working surface of the ladle bottom refractory material is in direct contact with the high-temperature molten steel, and the temperature of the non-working surface of the ladle bottom refractory material is relatively low. During the cycle of receiving molten steel → pouring molten steel → hot repair of the ladle → receiving molten steel, the temperature of the ladle is constantly changing, and the volume of the ladle bottom refractory material changes accordingly. Due to the existence of the temperature gradient of the ladle bottom refractory material and the different expansion coefficients of the degenerate layer and the original layer of the ladle bottom refractory material, the corresponding volume changes of each layer from the working surface to the non-working surface of the ladle bottom refractory material are different, which causes shear force on the ladle air brick, causing transverse cracks in the ladle air brick, and even causing transverse fractures in the ladle air brick.