I. Core Functions of Tundish
1.1 Operational Roles
The tundish serves as a critical transition device in continuous casting, linking ladles and mold systems. Its key functions include:
Molten steel distribution: Channels steel to multiple molds in multi-strand casting Flow stabilization: Maintains steady steel level (static pressure reduction ≥30%) Metallurgical refinement: Extends residence time (≥8 minutes) for inclusion flotation Multi-heat sequencing: Enables ladle replacement without speed reduction
II. Refractory Material System
2.1 Functional Classification
| Category | Components | Typical Materials |
|---|---|---|
| Lining Materials | Insulation/Permanent/Working | Alumino-silicate boards, Mullite castables |
| Flow Stabilizers | Dam/Impact plates | High-alumina precast blocks |
| Flow Controllers | Stopper/Slide gate/Nozzles | MgO-C composites |
2.2 Performance Criteria
Thermal stability: Must withstand extreme working conditions up to 1600°C Erosion resistance: Tolerate FeO-CaO slag corrosion rates <2 mm/hour Thermal shock resistance: Sustain >15 thermal cycles (ΔT=200°C/min) Gas permeability: Maintain 18-22% porosity for efficient gas release Constructability: Achieve initial setting time ≤45 minutes for rapid repairs
III. Lining Structure Optimization
3.1 Layered Configuration
| Layer | Thickness (mm) | Material | Key Parameters |
|---|---|---|---|
| Insulation | 10-30 | Alumino-silicate fiberboard | λ≤0.15 W/m·K |
| Permanent | 100-200 | Mullite self-flow castable | Density≥2.85 g/cm³ |
| Working | 20-50 | MgO-CaO spray coating | MOR≥10 MPa @1500°C |
3.2 Critical Components
Nozzle seat bricks: Use corundum-spinel composites (CTE match >90%) Slag dams: Precast high-alumina blocks (Al₂O₃≥75%) with ceramic filters Bottom protection: Prioritize zirconia precast (ZrO₂≥65%)
IV. Refractory Application Guidelines
4.1 Material Comparison
| Material | Temp. Range | Advantages | Limitations |
|---|---|---|---|
| MgO-Cr₂O₃ bricks | 1550-1650°C | Erosion rate <3 mm/hr | ≤5 thermal shock cycles |
| SiC bricks | 1450-1600°C | Thermal conductivity 18 W/m·K | Requires oxidation coating |
| Al₂O₃-ZrO₂ bricks | 1500-1580°C | Cost-performance optimal | Unsuitable for high-CaO slag |
4.2 Construction Protocols
Surface preparation: Maintain spray gun pressure at 0.5±0.1 MPa Preheating regime: Follow 25°C/h ramp rate with 6h holding at 800°C Maintenance cycle: Perform working layer repairs every 10-12 heats
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