Chromite sand is used as molding sand for steel and iron castings.
Chromium ore sand (chromite sand) is the preferred specialty facing sand/core sand for steel and iron casting molds, especially for large/thick-walled castings. Its core advantages include high refractoriness, sand-repellency, strong chilling, and low thermal expansion, significantly enhancing casting quality and process stability.
1. Core Performance Advantages (Suitable for High-Temperature Cast Steel / Cast Iron Scenarios)
Extremely high refractoriness and thermal stability
The refractoriness exceeds 1900°C, with a melting point of approximately 2180°C, far surpassing the pouring temperatures of cast steel or cast iron, remaining non-melting and non-disintegrating at high temperatures.
High chemical inertness, does not react with molten steel, iron water, iron oxide, or alkaline slag, effectively preventing thermal chemical sand adhesion.
Excellent anti-sand adhesion capability (two major mechanisms)
Solid-phase sintering for impermeability: Under high temperatures, sand particles sinter into a dense layer, physically blocking molten metal infiltration and eliminating mechanical sand adhesion.
Excellent wetting resistance: It exhibits a large wetting angle against molten steel/iron, making it difficult to be penetrated by metal liquid. The cast surface is smooth and easy to clean.
High thermal conductivity (quenching effect)
The thermal conductivity is 3–5 times that of silica sand, enabling it to replace chill blocks for accelerated cooling, grain refinement, sequential solidification, and reduced shrinkage porosity, shrinkage cavities, and thermal cracking.
Particularly suitable for castings such as thick-walled cast steel, ductile iron, and high-manganese steel that require controlled cooling and uniform microstructure.
Low thermal expansion coefficient
With minimal volumetric changes upon heating, it significantly reduces thermal expansion-induced issues such as vein patterns, sand inclusion, and casting cracking, ensuring dimensional accuracy.
II. Typical Applications in Cast Steel / Cast Iron
Large / thick-walled cast steel parts (alloy steel, stainless steel, high manganese steel): Fully coated with chrome sand or used as surface sand / locally reinforced sand, to prevent sticking, control thermal cracking, and promote sequential solidification.
Cast iron parts (ductile iron, gray iron): Thick-walled / hot spot areas are quenched with chrome sand to reduce shrinkage, improve graphite morphology, and enhance strength and surface quality.
Easy-to-adhere-to-sand / prone-to-deformation areas: Replace silica sand with local surface sand/core sand to address vein marks, sand adhesion, and dimensional deviations.
Coating aggregate: After grinding, it is used in casting coatings to enhance refractoriness and anti-adhesion properties.