Cast Steel Grit

Shandong Haishan Industrial Technology produces cast steel grit at a facility with 100,000 tons of annual capacity and distributes it to customers in over 50 countries. This angular abrasive is made from high carbon steel and is designed for heavy industrial cleaning where cutting force matters more than peening effect. It is used to remove thick mill scale, heavy rust, and sand from castings and steel structures. It is not the right choice for precision components, thin plates, or applications that require surface strengthening.

Manufacturing and Heat Treatment

The production route includes melting high carbon steel, atomizing it into shot, then crushing the shot into angular particles. The crushed material is screened through multiple sieves to control particle size distribution. A dual quenching and tempering cycle is then applied to achieve the target hardness and toughness. This process removes spherical or rounded grains, leaving a product with sharp, irregular edges that cut rather than bounce.

Hardness is normally held between HRC 42 and 55, depending on the specific grade. Test methods follow SAE J444 for size distribution and GB/T 18838 for chemical and mechanical properties.

Key Specifications

Different grades are available within the hardness range. GP grade typically falls at the lower end, GL in the middle, and GH at the upper end. The exact grade should be selected based on the workpiece hardness and the type of contaminant to be removed.

How Cast Steel Grit Performs

• Aggressive cutting: Angular edges concentrate stress on a small contact area, making it effective for removing hard oxide scale, thick rust, and foundry sand from castings.
• Controlled breakdown: The tempered martensitic structure helps the particles resist premature shattering, allowing multiple reuse cycles in wheel blast machines.
• Anchor profile creation: On carbon steel, cast steel grit typically produces a surface profile in the range of 40–100 μm, depending on particle size and blasting pressure. This profile is suitable for many heavy-duty coating systems.
• Recyclability: In closed-loop blast systems, the working mix can be maintained by adding new grit as spent particles break down. This reduces long-term abrasive cost compared to single-use mineral abrasives.

Where Cast Steel Grit Should Not Be Used

This product is not intended for shot peening or surface strengthening. Its angular shape creates a rough surface and removes material; it does not produce the compressive stress layer required for fatigue life improvement. It is also not suitable for thin steel plate (below 6 mm) or precision-machined parts, as the aggressive cutting may cause deformation or excessive metal removal.

Selecting the Right Particle Size

The table below provides a general guide for matching cast steel grit size to common cleaning tasks. Final selection should be confirmed by testing on the actual workpiece.

Larger particles remove heavy contaminants faster but leave a deeper profile. Smaller particles produce a smoother finish but may require more time to achieve the same cleanliness level.

Cast Steel Grit vs. Steel Shot

These two abrasives are often used together in the same blast machine, but they serve different purposes. The table below summarizes the key differences.

For many structural steel applications, a mixture of steel grit and steel shot is used to balance cleaning speed and surface profile. The ratio depends on the coating specification and the condition of the steel.

Common Applications

• Removal of high-temperature oxide scale from iron and steel castings
• Heavy rust removal from waste steel, second-hand plates, and aged structures
• Surface preparation of large steel components before high-build anti-corrosion coating
• Descaling of hot-rolled steel plate and sections
• Blast cleaning of ship plates, storage tanks, and pressure vessels

Quality Control and Documentation

Every batch of cast steel grit is tested for chemical composition, hardness, and particle size distribution. The laboratory uses a direct-reading spectrometer for chemistry, a Rockwell hardness tester for hardness, and a sieve shaker for size analysis. Certificates of analysis and test reports are supplied with each shipment. Additional documents such as metallographic structure reports and ISO 9001:2015 certificates are available on request.

Packaging and Storage

Cast steel grit is packed in 25 kg bags with a moisture-resistant PE inner liner and a woven polypropylene outer bag. 1,000 kg bulk bags on pallets are available for larger orders. For export, pallets comply with ISPM 15 requirements. Store in a dry, covered area to prevent moisture absorption. Bags should be kept off the ground and away from direct rain.

Frequently Asked Questions

What is the difference between cast steel grit and steel shot?

Cast steel grit has angular, irregular edges that cut and scrape the surface, making it suitable for heavy rust and scale removal. Steel shot is spherical and works by impact, leaving a smoother surface and providing a peening effect. Many blast machines use a mixture of both to balance cleaning efficiency and profile.

What hardness should I choose for heavy rust removal?

For heavy rust, a hardness range of HRC 48–55 is often effective because it provides strong cutting action while still maintaining enough toughness to avoid premature shattering. If the rust is moderate, HRC 42–50 may be sufficient and more economical.

Can cast steel grit be used for shot peening?

No, cast steel grit is not recommended for shot peening. Its angular shape removes material rather than creating a uniform compressive stress layer. For peening applications, use spherical steel shot or conditioned cut wire shot.

Is cast steel grit suitable for stainless steel surfaces?

No, cast steel grit is made from carbon steel and can cause ferrous contamination on stainless steel. For stainless steel, use stainless steel abrasive or non-metallic media.

What surface profile can be achieved with cast steel grit?

On carbon steel, cast steel grit typically produces a profile between 40 and 100 μm, depending on particle size, hardness, and blasting parameters. Use replica tape or a surface profile gauge to verify the actual profile before coating.

Can cast steel grit be recycled?

Yes, in closed-loop wheel blast machines, cast steel grit can be recycled multiple times. Particle breakdown occurs gradually, and the working mix is maintained by adding new grit. The recycling life depends on the grade, blast pressure, and workpiece hardness.