AISI 321 Stainless Steel Balls
Ball Bearing
Heat Resistant & Stabilised Corrosion Performance
Our AISI 321 stainless steel ball range is designed to deliver excellent resistance to high temperatures, oxidation, and intergranular corrosion. As a titanium-stabilised austenitic stainless steel, AISI 321 is ideal for applications exposed to elevated temperatures where standard grades such as 304 may suffer from carbide precipitation. At Atlas Ball & Bearing, we supply AISI 321 balls to precise specifications with full manufacturing capability and technical support.
150
Precision Ball Diameter
Why Choose AISI 321 Stainless Steel Balls?
AISI 321 stainless steel balls are designed for applications requiring resistance to high temperatures and improved protection against intergranular corrosion. The addition of titanium stabilises the material, making it particularly effective in environments involving heat cycling or welding.
Key Benefits
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Excellent resistance to high temperatures and oxidation
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Titanium stabilisation prevents carbide precipitation
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Resistant to intergranular corrosion after heating or welding
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Good corrosion resistance in a range of industrial environments
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Suitable for elevated temperature mechanical applications
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Maintains strength and stability under thermal stress
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Reliable performance in heat-exposed systems
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Consistent dimensional accuracy for precision components
Manufacturing & Supply
We are capable of manufacturing and supplying loose AISI 321 stainless steel balls in nearly every variation of grade, maintaining an extensive stock with sizes ranging from 0.2mm to 150mm in diameter.
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Additionally, we offer a bespoke ball manufacturing service, which follows the same process controls and traceability but uses a customer’s own material. For further details, please email us or call +44 (0) 1922 710515.
Applications
AISI 321 stainless steel balls are commonly used in applications requiring resistance to elevated temperatures and protection against intergranular corrosion.
Typical applications include:
- Precision-engineered components
- Aerospace and high-temperature systems
- Heat exchangers and furnace components
- Exhaust systems and thermal processing equipment
- Chemical processing equipment
- Welded assemblies exposed to heat
- Industrial machinery operating at elevated temperatures
AISI 321 balls are available in a wide range of sizes and tolerances to meet both standard and precision engineering requirements, particularly where thermal stability and corrosion resistance are critical.
Why Atlas Ball & Bearing?
- UK-based manufacturer and supplier of precision-engineered stainless steel balls
- Extensive stock across a wide range of stainless steel grades
- Consistent quality control and dimensional accuracy
- Technical support for engineering and industrial applications
- Fast UK and international delivery
- Bespoke manufacturing to exact customer requirements
Related Materials
304 Stainless Steel Balls
440C Stainless Steel Balls
316 Stainless Steel Balls

Useful terms and definitions
Batch or Lot:
A defined quantity of balls manufactured under conditions presumed to be uniform and which is considered an entity.
Nominal Ball Diameter:
The diameter value that is used for the general identification of a ball size.
Single Ball Diameter:
The distance between two parallel planes tangential to the actual ball surface.
Diameter Tolerance per Batch:
The allowed difference between the smallest measured ball diameter and the largest ball diameter within the same batch or lot quantity.
Sphericity:
A measure of roundness expressed as the difference between the measured roundness of a ball and a theoretically perfectly round ball.
Surface Finish or Roughness:
A measure of the texture of a surface. It is quantified by the vertical deviations of the actual surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth.
Ball Grades
| Grade | Diameter Tolerance per Ball | Sphericity | Diameter Tolerance per Unit Container | Basic Diameter Tolerance | Maximum Surface Roughness Micro | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Inch | µ | Inch | µ | Inch | µ | Inch | µ | Inch | µ | |
| 3 | .000003 | 0.076 | .000003 | 0.076 | .000005 | 0.127 | ±.00003 | ± 0.076 | 0.5 | 0.013 |
| More details about Grade 3... | ||||||||||
| 5 | .000005 | 0.127 | .000005 | 0.127 | .00001 | 0.25 | ±.00005 | ± 0.127 | 0.8 | 0.02 |
| More details about Grade 5... | ||||||||||
| 10 | .000010 | 0.25 | .000010 | 0.25 | .00002 | 0.51 | ±.0001 | ± 2.5 | 1.0 | 0.025 |
| More details about Grade 10... | ||||||||||
| 15 | .000015 | 0.38 | .000015 | 0.38 | .00003 | 0.76 | ±.0001 | ± 2.5 | 1.2 | 0.03 |
| More details about Grade 15... | ||||||||||
| 25 | .000025 | 0.63 | .000025 | 0.63 | .00005 | 1.27 | ±.0001 | ± 2.5 | 1.5 | 0.038 |
| More details about Grade 25... | ||||||||||
| 50 | .00005 | 1.27 | .00005 | 1.27 | .0001 | 2.5 | ±.0002 | ± 5 | 3.0 | 0.075 |
| More details about Grade 50... | ||||||||||
| 100 | .0001 | 2.5 | .0001 | 2.5 | .0002 | 5 | ±.0005 | ± 5 | 5.0 | 0.125 |
| More details about Grade 100... | ||||||||||
| 200 | .0002 | 5 | .0002 | 5 | .0004 | 10 | ±.0010 | ± 10 | 8.0 | 0.2 |
| More details about Grade 200... | ||||||||||
| 300 | .0003 | 7.5 | .0003 | 7.5 | .0006 | 15 | ±.0015 | ± 37.5 | N/A | N/A |
| More details about Grade 300... | ||||||||||
| 500 | .0005 | 12.5 | .0005 | 12.5 | .001 | 25 | ±.002 | ± 50 | N/A | N/A |
| More details about Grade 500... | ||||||||||
| 1000 | .001 | 25 | .001 | 25 | .002 | 50 | ±.005 | ± 125 | Not Applicable | Not Applicable |
| More details about Grade 1000... | ||||||||||
| 2000 | .002 | 50 | .002 | 50 | .004 | 100 | ±.005 | ± 125 | N/A | N/A |
| More details about Grade 2000... | ||||||||||
Sample Our Work!
Take the first step towards precision and quality with our expert services. At Atlas Ball & Bearing, we’re committed to delivering top-notch precision balls and rollers for a wide range of industries, including gas, oil, medical, and transportation. Our dedicated team is ready to assist you with custom solutions tailored to your specific needs. Experience the Atlas Ball & Bearing difference now!