| C | Si | Mn | Cr | Ni | P | S | |
|---|---|---|---|---|---|---|---|
| CG40Cr | 0.37-0.44% | 0.17-0.37% | 0.50-0.80% | 0.80-1.10% | ≤0.30% | ≤0.035% | ≤0.035% |
| CG08 | 0.06-0.10% | 0.10-0.30% | 0.30-0.60% | 0.50-0.80% | ≤0.20% | ≤0.030% | ≤0.030% |
| SAE 8620 | 0.18-0.23% | 0.15-0.35% | 0.70-0.90% | 0.40-0.60% | 0.40-0.70% | ≤0.035% | ≤0.040% |
| Material | Heat-treatment route | Hardness reference | ||||
|---|---|---|---|---|---|---|
| 40Cr | Quenching and tempering | Approximately HRC 28–55 across different tempering conditions | ||||
| SAE 8620 | Carburizing, quenching and tempering | Surface HRC 58–62 is a common carburized target | ||||
| Item | Parameters | ||||
|---|---|---|---|---|---|
| Elastic Modulus | 200-210 GPa | ||||
| Thermal Conductivity | 40-45 W/(m·K) | ||||
| Coefficient of Thermal Expansion | 11.5-12.5 (10⁻⁶/°C) | ||||
| Density | 7.85 g/cm³ | ||||
| Hardness — 52100/GCr15 | HRC 60 – 66, through-hardened | ||||
| Hardness — SAE 8620 | Surface HRC 58 – 62 after carburizing, tough core | ||||
| Hardness — 40Cr | HRC 28 – 55 by tempering temperature | ||||
| Grade | Maximum single-ball diameter variation V_Dws (µm) | Maximum lot diameter variation V_DwL (µm) | Maximum surface roughness Ra (µm) | ||||
|---|---|---|---|---|---|---|---|
| G10 | 0.25 | 0.50 | 0.020 | ||||
| G16 | 0.40 | 0.80 | 0.025 | ||||
| G20 | 0.50 | 1.00 | 0.032 | ||||
| G28 | 0.70 | 1.40 | 0.050 | ||||
| G40 | 1.00 | 2.00 | 0.060 | ||||
| G60 | 1.50 | 3.00 | 0.080 | ||||
| G100 | 2.50 | 5.00 | 0.100 | ||||
| G200 | 5.00 | 10.00 | 0.150 | ||||
| Property | Alloy Steel (52100/40Cr/8620) | Carbon Steel Balls | 420 Stainless Steel Balls | 304/316 Stainless Balls |
|---|---|---|---|---|
| Wear resistance | Excellent | Very good | Good | Fair |
| Corrosion resistance | Low (oil protection needed) | Low | Moderate | Excellent |
| Load capacity | Highest | High | Medium | Low–Medium |
| Best for | Bearings, grinding, valves | Casters, slides | Mild-corrosive bearings | Food, medical, marine |
Changzhou Risheng Steel Ball Co., Ltd. is located in Wujin District, Changzhou, in the Taihu Lake region within two hours of Shanghai. Founded in June 1995, the company specializes in the R&D, manufacturing and export of precision steel balls. Building on the technical foundation of the Wujin Metal Ball Research Institute, Risheng primarily produces bearing steel balls (AISI 52100), stainless steel balls (AISI 201/304/316/420/430/440) and carbon steel balls (AISI 1015/1045/1085) in diameters from 0.8 mm to 25.4 mm, in precision grades from G100 up to G10. We also supply custom alloy steel balls from 0.5 mm to 100 mm, as well as copper balls, flying saucer steel balls, ceramic balls and other special metal balls.
1. Rust-Preventive Protection
Rust-preventive oil and moisture-resistant packaging help protect 40Cr and SAE 8620 steel balls during storage and transport. Tell us if the preservation method must meet cleaning, assembly or oil-compatibility requirements.
2. Protective Inner Packaging
Inner packaging is selected according to ball size, weight and surface requirements. Where contact marks are unacceptable, specify separated packing or additional surface protection.
3. Export Outer Packaging
Cartons, drums and pallet arrangements are selected according to shipment weight and handling requirements. Confirm pack weight and shipping marks when placing the order.
4. Batch Labels and Identification
Specify the material grade, nominal diameter, precision grade, quantity and batch information required on the labels. Customer part numbers and barcode requirements can be reviewed with the order.
With an elastic modulus of 200-210 GPa and thermal expansion coefficient of 11.5-12.5×10⁻⁶/°C, they maintain stability in temperatures from -50°C to 150°C, suitable for varied operating conditions.
They offer high precision with grades G10-G200 (tolerances ±0.0025mm to ±0.025mm) and a surface roughness of Ra 0.02-0.05μm, ensuring smooth, low-friction performance in high-speed or precision applications.
They are used in rolling bearings, grinding media, valves, and mechanical transmission systems, particularly in automotive (e.g., gearboxes), industrial machinery, mining equipment, and precision instruments.
Alloy steel balls are made from low-alloy steels like CG40Cr, CG08, or SAE8620, containing elements such as chromium (0.4-1.1%), nickel (up to 0.7%), and molybdenum (up to 0.25%). These elements enhance hardness, toughness, and wear resistance.
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