AISI 304 vs AISI 316: Which Stainless Steel for Rope and Wire?
2 min read OSAK
The two grades most commonly found in stainless steel wire rope, wire and fittings are AISI 304 and AISI 316. For fittings they are often called A2 and A4. Although both are stainless, the difference is significant depending on where they are used.
The key difference: molybdenum
AISI 304 contains about 18% chromium and 8% nickel. AISI 316 contains, in addition to chromium and nickel, about 2–3% molybdenum. Molybdenum markedly increases resistance to pitting corrosion, especially in salt water and chloride-bearing environments.
Which one should you choose?
| Environment / application | Recommendation |
|---|---|
| Indoors, dry environment, decoration | AISI 304 |
| General outdoor (urban) | AISI 304 or 316 |
| Seaside, boats, piers | AISI 316 |
| Around pools, chemical environments | AISI 316 |
| Food and medical | 304/316 depending on the application |
Is the magnet test reliable?
Annealed 304 and 316 are not magnetic; however, cold-drawn wire and rope can show slight magnetism. The magnet test alone is therefore not a reliable way to tell the grades apart; check the material certificate.
Price
Because of its molybdenum and higher nickel content, 316 is more expensive than 304. But using 304 by the sea and facing early surface staining and corrosion costs more in the long run.
We offer both grades in stainless wire rope, stainless wire and stainless fittings.
