Key Takeaways
· Quick temperature changes can cause thermal shock. This can crack ladle shrouds. Heating slowly and checking the temperature can stop this damage.
· Mechanical stress from moving and using parts can cause cracks. Storing parts carefully and handling them right helps lower this risk. Installing them the correct way also helps.
· Hot slag can wear down and get into refractory materials. This makes them weaker. Using strong materials and checking slag conditions can protect the parts.
· The quality of materials is important. Good raw materials and careful making of parts help stop cracks. Having the right amount of porosity makes parts stronger and better at handling shock.
· Good design and alignment lower stress and stop leaks. Smooth shapes and tight fits help keep ladle shrouds and nozzles strong. Checking them often also helps.
1. Thermal Shock
Temperature Changes
When the temperature changes quickly, it puts stress inside refractory materials. During ladle preheating, the working layer gets hot on one side and stays cool on the other. This big difference in temperature causes strong pulling stress at the top of the working layer. Sometimes, this stress can get as high as 39.06 MPa. Damage often starts at the top and near the sidewall burner nozzles. If the ladle heats up too fast, alumina-magnesia castables get stiffer but weaker. The material turns more brittle and can break more easily. When steel is poured, the ladle shroud faces sudden heat, which also builds up stress.
Tip: Teams should watch temperature changes during preheating and pouring. Using thermal imaging cameras can help find hot spots and uneven heating. These signs show where cracks might happen.
Crack Formation
Thermal shock cracks show up a lot in high-temperature furnace linings and steel ladles. These parts go through fast heating and cooling many times. When the temperature changes too quickly, the refractory grows or shrinks more than it can handle. If the material is brittle, especially under 1100°C, cracks form easily. Big parts, uneven heating, and outside forces make cracking worse. Changes in the material’s structure can also raise the risk.isostatical pressed refractory
· Common scenarios for thermal shock cracking:
1. Ladle preheating with fast temperature rise.
2. Steel pouring with sudden molten metal exposure.
3. Quenching or cooling steps in steelmaking.
4. High-temperature furnace linings in steel, cement, glass, and ceramics.
Thermal shock can cause early failure with small and large cracks. Operators often see pieces breaking off, falling apart, and cracks along the ladle shroud and nozzle. Checking often and tracking temperature changes helps teams stop damage before it gets worse. Using materials that handle thermal shock better and heating slowly can help lower the chance of cracks. Slide gate plate
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