304 Stainless Steel Ball（AISI 304 / SUS 304）
- Most versatile and economical austenitic 304 stainless steel ball
- Composition: 18% Chromium + 8% Nickel (18-8 stainless steel)
- Characteristics: Excellent corrosion resistance, non-magnetic (very weak magnetism after demagnetization), good toughness and ductility
- Corrosion resistance: Suitable for general corrosive environments such as atmosphere, water, steam, grease, and food.
- Unsuitable for: Strong corrosive environments such as those with high chloride ion resistance (e.g., seawater, salt spray).
- Common applications: Furniture drawer slides, spray bottle pump heads, food processing equipment, low-load bearings, cosmetic mixing balls, etc.
- Hardness: HRC ≤ 26 (annealed state)
316 Stainless Steel Ball（AISI 316 / SUS 316 / 316L）
- Medical-grade and marine-grade stainless steel balls
- Composition: 16-18% Chromium + 10-14% Nickel + 2-3% Molybdenum (molybdenum-containing stainless steel)
- Features: Superior resistance to pitting and chloride ion corrosion compared to 304; resistant to seawater, salt spray, acids, and alkalis; low magnetic or non-magnetic
- Common specifications: 316 and lower carbon 316L (carbon content ≤0.03%) are interchangeable; 316L is more suitable for welding applications.
- Common applications: Medical devices, pharmaceutical equipment, marine environment parts, jewelry, spray pumps, high-end cosmetic bottle pump heads
- Hardness: HRC ≤ 26
420 Stainless Steel Ball（AISI 420 / SUS 420）
- Magnetic martensitic stainless steel balls, heat-treatable
- Composition: 12-14% chromium, carbon content above 0.15%
- Features: Some corrosion resistance (not as good as 304/316), but can achieve higher hardness through quenching and tempering
- Hardness range: HRC 50-58 (after quenching)
- Advantages: Good wear resistance, moderate cost, strong magnetism
- Common applications: Medium to high load bearings, slide rails, power tools, valves, nail clippers, and other applications requiring a certain level of hardness.
440 Stainless Steel Ball（AISI 440C / SUS 440C）
- Highest hardness and wear resistance stainless steel balls
- Composition: 16-18% chromium, carbon content 0.95-1.2%
- Features: Can be quenched to maximum hardness; corrosion resistance is still better than the 420 series, but not as good as 316.
- Hardness: HRC 58-65 (440C can reach HRC 60+)
- Common grades: 440A, 440B, 440C (440C has the strongest hardness and wear resistance)
- Applications: High-end precision bearings, aerospace parts, surgical instruments, high-precision valves, military products
