316 is the corrosion answer when nothing else survives: seawater, brine, acids, sterilising chemicals. It cannot be hardened, so its races are soft and its load rating is roughly half that of a chrome steel bearing.
| Designations | 316 (AISI) · 1.4401 / 1.4404 (EN) · SUS316 (JIS) · X5CrNiMo17-12-2 |
|---|---|
| Chemistry | 16–18% Cr · 10–14% Ni · 2–3% Mo · ≤0.08% C |
| Hardness | 25–30 HRC — not hardenable by heat treatment |
| Density | 8.00 g/cm³ |
| Max service temperature | 300 °C (mechanical limit, not lubricant limit) |
| Corrosion resistance | Excellent — seawater, chlorides, most organic and many inorganic acids |
| Magnetic | Essentially non-magnetic (slightly permeable after cold work) |
| Load rating | ≈40–50% of 52100 at equal size |
| Relative cost | 3–4× 52100 |
Austenitic stainless is tough, ductile and corrosion-resistant precisely because its crystal structure does not transform on quenching. That same property means it cannot be hardened by heat treatment: the raceway stays at 25–30 HRC, and a soft raceway deforms under rolling contact instead of resisting fatigue. The bearing works, but the allowable load is a fraction of a hardened steel bearing's.
The molybdenum addition is the difference from 304. It stabilises the passive layer against chloride attack, which is why 316 survives seawater and 304 does not. For a marine deck fitting, a chemical dosing pump or a sterilisation tunnel, that difference decides whether the bearing lasts a season or a month.
Start from the load the position actually carries, then compare it with the 316 rating rather than the steel rating you would normally use. Because the material is softer, deflection under load is larger and the bearing is less tolerant of misalignment and edge loading. Where the margin is thin, the honest answers are a bigger bearing, more bearing positions, or a different material — zirconia ceramic carries more load at similar corrosion resistance.
| Property | 316 | 440C | Zirconia (ZrO2) | 52100 + zinc-nickel |
|---|---|---|---|---|
| Hardness | 25–30 HRC | 58–60 HRC | ≈1200 HV | 59–65 HRC |
| Load rating | ≈40–50% of 52100 | ≈85–90% | High, but brittle | Baseline |
| Seawater | Excellent | Pits | Excellent | Poor |
| Max temp | 300 °C | 250 °C | 400 °C | 120 °C |
| Magnetic | No | Yes | No | Yes |
| Cost | 3–4× | 2.5–3.5× | 6–10× | 1.3–1.6× |
Light-load marine and chemical positions in standard ISO sizes.
Read →Rod ends and linkages where 316 pairs with a PTFE liner.
Read →Where the fluid decides the material and the load is modest.
Read →Same corrosion resistance, far higher hardness — at a price.
Read →Yes, and it is one of the few metallic options that can. Keep the load light, avoid stagnant crevices and remember that 316 is not immune — it resists, it does not ignore. Zirconia ceramic is the higher-load option.
Cold working — pressing, swaging or severe machining — can transform some austenite to martensite and raise permeability. A properly annealed 316 bearing is essentially non-magnetic; a strongly magnetic one suggests the wrong grade or heavy cold work.
The alloy is widely accepted for food contact, but the bearing is a machine element, not a contact surface. What matters in practice is the lubricant (NSF H1) and whether the housing can be cleaned.
Roughly half. If a 440C bearing has a dynamic rating of 14 kN, the 316 equivalent is around 6–7 kN. That is the number to design against, not the steel one.
| Industry | Duty | Where it fits | |
|---|---|---|---|
| Pumps & Compressors | continuous running, thrust reversal and process fluid along the shaft | Chemical & seawater | Detail → |
| Conveyors & Bulk Handling | slow speed, abrasive dust and frame misalignment | Chemical & fertiliser | Detail → |
Model numbers, quantities and the application — we reply with brand options, price and lead time within 30 minutes on working days.