The grade standards of stainless steel balls are mainly classified based on the chemical composition and performance of the material, with different grades corresponding to different applications:
Material Grade Standards
- 200 Series (Chromium-Nickel-Manganese): Featuring an austenitic structure, it has good corrosion resistance and is commonly used in scenarios such as hardware accessories.
- 300 Series (Chromium-Nickel): With an austenitic structure, it is non-magnetic and has strong rust resistance, suitable for scenarios like medical equipment and food machinery.
- 400 Series (Chromium-Based): Including martensitic and ferritic structures, it has high hardness (e.g., 440C can reach HRC 56-58) and combines wear resistance and corrosion resistance. It is mostly used in scenarios such as aerospace bearings and precision valves.
Performance Standards
The performance standards of stainless steel balls include:
- Dimensional Accuracy: Diameter variation ≤ 25 μm, sphericity error ≤ 25 μm;
- Crushing Load: Ensuring the steel balls do not break;
- Heat Treatment Quality: Achieving high hardness (e.g., 440C has a hardness of HRC 56-58) and wear resistance through heat treatment.
International Standards
The classification systems of the International Organization for Standardization (ISO) and the American Iron and Steel Institute (AISI) are adopted. For example:
- AISI 316 corresponds to 316 stainless steel balls, which contain molybdenum to enhance oxidation resistance and corrosion resistance, with a hardness of HRC 20-26;
- AISI 304 is non-magnetic and has strong rust resistance, suitable for food machinery.
Different materials should be selected according to the application scenario: for example, 440C is preferred for high wear-resistant scenarios, 304/316 for conventional corrosion protection, and 201 series is commonly used for hardware accessories.
