AFS 40–45 Chromite Sand for Steel Casting
Product Overview
AFS 40–45 chromite sand is a high‑grade foundry sand refined from natural chromite ore, mainly composed of magnesiochromite and chromite spinel (FeO·Cr₂O₃). It features low thermal expansion, high thermal conductivity, excellent refractoriness, and chemical inertness against molten steel, making it the preferred molding sand for high‑quality steel castings.
Typical Specifications
| PHYSICAL PROPERTIES(TYPICAL) | AVERAGE CHEMICAL COMPOSITION(TYPICAL) | ||
| PH | 7-9 | Cr2O3 | ≥46.0% |
| Color | Black | SiO2 | ≤1.0% |
| Acid Amount | ≤2m | Fe2O3 | ≤26.5% |
| Soil% | ≤0.1 | CaO | ≤0.30% |
| Bulk Density | 2.5-3.0g/cm3 | MgO | ≤10.0% |
| Specific Gravity | 4.0-4.8g/cm3 | Al2O3 | ≤15.5% |
| Moisture | ≤0.1% | P | ≤0.003% |
| Sintered temperature | ≥1800℃ | S | ≤0.003% |
| Free Acid | 0 | Cr/Fe | 1.55:1 |
| Filling density | 2.6g/cm3 | ||
| Melting temperature | ≥2180℃ | ||
Grain Size (AFS 40–45)
- AFS Fineness Number: 40–45
- Main particle size range: 212–425 μm (40–70 mesh)
- Uniform particle distribution, suitable for resin sand, sodium silicate sand, and no‑bake molding systems.
Main Applications in Steel Casting
- Ideal for carbon steel, alloy steel, stainless steel, high‑manganese steel and other reactive steel grades.
- Used as facing sand to prevent metal penetration, veining, and burn‑on defects.
- Provides strong chilling effect to improve solidification, reduce shrinkage cavities and porosity in heavy section castings.
- Widely used in wind power castings, engineering machinery, valves, pump bodies, railway parts and high‑precision structural steel castings.
Advantages
- Extremely low thermal expansion → minimizes mold cracking and dimensional distortion.
- High thermal conductivity → accelerates directional solidification.
- Chemically inert to molten steel → smooth casting surface, easy cleaning.
- Good collapsibility → improves shakeout efficiency.
- Suitable for both small and large heavy steel castings.