Corrosion resistance that enables use in a wide variety of environments
Stainless steel balls offer excellent corrosion resistance and are primarily used in corrosive environments such as valves. There are two types—martensitic and austenitic—each differing in durability and corrosion resistance.
Characteristics
Martensitic (SUS440C) Hard and highly durable
Martensitic stainless steel balls offer not only excellent corrosion resistance but also remarkable durability. Specifically, SUS440C material boasts strength comparable to high-carbon chromium bearing steel (SUJ2), making it ideal for use in precision bearings, high-pressure valves, and safety valves. It is also magnetic.
Austenitic (SUS304, SUS316) Excellent corrosion resistance
Austenitic stainless steel balls offer superior corrosion resistance compared to martensitic types. SUS304 material features a low carbon content, resulting in minimal carbide precipitation. With added molybdenum, SUS316 material provides even greater corrosion resistance than SUS304. Both are non-magnetic.
Applications（Examples）
- Stainless steel bearings (SUS440C)
- Used in high-humidity environments where ordinary iron would rust. Their high corrosion resistance and hardness contribute to long life.
- Ball valves (SUS304, SUS316)
- Used in high pressure environments that require corrosion resistance, they offer safety and ease of use with their hardness and smooth operation.
- Non-magnetic stainless steel bearings (SUS304)
- Austenitic stainless steel is non-magnetic and is used in medical settings, such as in MRI machines.
Our high-quality balls provide smoothness in any environment.
From our Product Representatives
Even though we use the term ‘stainless steel’ broadly, there are significant differences between martensitic and austenitic types.
Notably, martensitic SUS440C is rare among stainless steels for its use in bearings, especially in food machinery, which is prone to high-humidity. Furthermore, the martensitic type offers superior corrosion resistance compared to the austenitic type and is non-magnetic, making it suitable for specialized environments.
We can provide recommendations to meet your specific applications, so please don’t hesitate to contact us.
Product Specifications
1. Chemical composition of material (%)
| C | Si | Mn | P | S | Ni | Cr | Mo | |
|---|---|---|---|---|---|---|---|---|
| マルテンナイト系 | ||||||||
| SUS440C JIS standard | 0.95 to 1.20 | 1.00 or less | 1.00 or less | 0.040 or less | 0.030 or less | (1) | 16.00 to 18.00 | (2) |
| オーステナイト系 | ||||||||
| SUS304 JIS規格 | 0.08以下 | 1.00以下 | 2.00以下 | 0.045以下 | 0.030以下 | 8.00～10.50 | 18.00～20.00 | – |
| SUJ316 JIS規格 | 0.08以下 | 1.00以下 | 2.00以下 | 0.045以下 | 0.030以下 | 10.00～14.00 | 16.00～18.00 | 2.00～3.00 |
1) Nickel must not exceed 0.60%.
2) Molybdenum must not exceed 0.75%.
*The chemical compositions of stainless steel bars and stainless steel wire are the same.
2.Dimensions and dimensional accuracy
・ SUS440C
Conforms to Japanese Industrial Standard JIS B1501-2009
・ SUS304、SUS316
Dimensions
| Ball material classification | 呼び |
|---|---|
| Martensitic stainless steel balls | 1/8(3.175mm) to 1 1/2(38.100mm) |
| Austenitic stainless steel balls | 1/8(3.175mm) to 2(50.800mm) |
※（ ）内の値は、換算値を参考。
Dimensional accuracy (Unit: μm)
| Nominal range | Diameter tolerance | Lot diameter variation (max.) | Sphericity (max.) |
|---|---|---|---|
| 1/8(3.175mm) ～ 1/2(12.700mm) | ±15 | 2 | 2 |
| 9/16(14.288mm) ～ 2(50.800mm) | ±15 | 3 | 3 |
3. Hardness
・ SUS440C ⇒ 59to66 HRC
Mechanical Properties (Reference Values)
| Classification | 硬度(HV) | Corrosion resistance | Magnetic | |
|---|---|---|---|---|
| マルテンサイト系 ステンレス鋼球 | SUS440C | 800 | ◎ | Magnetic |
| オーステナイト系 ステンレス鋼球 | SUS304 | 200 | ◎◎◎ | Non-magnetic |
| SUS316 | 200 | ◎◎◎◎ | Non-magnetic | |
