Chrome ore foundry sand AFS45/55 for Railway Turnout Accessories Casting
Chrome ore foundry sand AFS 45/55 (particle size of about 0.25-0.35mm) is used as casting sand for railway turnout accessories. With its unique physical and chemical properties, it has excellent performance in high temperature stability and resistance to metal penetration. The following are its core advantages and mechanism of action:
1. Excellent high temperature stability
High temperature resistance. The melting point of chromite sand is as high as about 1850°C. That is much higher than the pouring temperature of cast iron (~1200°C) and cast steel (~1500°C). It is not easy to sinter or deform under the impact of high temperature molten metal, and maintains the dimensional stability of the casting.
Low thermal expansion coefficient: The thermal expansion rate is only 1/3 of that of silica sand, which reduces the cracking or burrs of the casting caused by thermal stress, and is particularly suitable for the casting of high-precision turnout accessories (such as point rails, slide bed plates, etc.).
2. Strong resistance to metal penetration
Chemical inertness.FeCr₂O₄ in chrome ore sand has extremely low reactivity with molten metal at high temperature. It can effectively prevent iron/steel liquid from penetrating into the gaps between sand particles. In the meantime, it reduces sand adhesion defects on the surface of castings, and reduce subsequent cleaning costs.
Dense structure. The particles have high hardness and few edges and corners (AFS 45-55 grade particle size distribution is uniform), which can form a tightly packed surface sand layer to block the penetration of molten metal.
3. Excellent cooling and solidification control
High thermal conductivity: The thermal conductivity of chrome ore sand is 2-3 times that of silica sand, which can accelerate the solidification of the casting surface, refine the grains, and improve the mechanical properties of turnout accessories (such as fatigue strength and wear resistance).
Reduce pores: Rapid cooling inhibits gas retention and reduces the risk of pores in castings, which is especially important for thick-section turnout components (such as frogs).
4. Improve casting quality
Resistance to alkaline slag erosion: Chromium ore sand has a stronger resistance to high manganese steel (such as Mn13 rolled steel for turnout) slag than silica sand, reducing inclusion defects caused by mold erosion.
Chrome ore sand AFS 45-55 has become an ideal choice for casting surface sand of railway turnout accessories (especially high-load, high-precision parts) with its three core advantages of high-temperature inertness, anti-penetration and fast cooling. Although the cost is higher than silica sand, it can significantly improve the qualification rate and service life of castings, and the comprehensive benefits are outstanding.
