1.4401 Stainless Steel Corrosion Resistant Flat Face Forged Steel Flange EN1092

1.4401 steel is a common European stainless steel grade, broadly equivalent to AISI 316. It's an austenitic stainless steel known for very good corrosion resistance, especially in chloride-containing environments like marine atmospheres or mildly saline solutions.

• Chromium (16.5–18.5%): Forms a passive chromium oxide film on the surface, giving the steel its "stainless" character. The higher Cr content improves resistance to oxidation and general corrosion.
• Nickel (10–13%): Stabilizes the austenitic structure, making the steel tough and non-magnetic (in solution-annealed condition). Improves overall corrosion resistance and toughness, especially at low temperatures.
• Molybdenum (2.0–2.5%): The key difference from 304-type stainless steels. Greatly enhances pitting and crevice corrosion resistance in chloride media (e.g., seawater, de-icing salts). This is why 1.4401 / 316 is often chosen for marine, chemical, and food-industry environments.
• Low Carbon (≤ 0.07%): Reduces the risk of chromium carbide precipitation at grain boundaries during welding and heat exposure, which helps maintain corrosion resistance. However, if excellent weldability and resistance to intergranular corrosion after welding are critical, the low-carbon variant 1.4404 (316L) is usually preferred.
• Controlled Impurities (P, S): Phosphorus and sulfur are kept low to avoid hot cracking and to maintain toughness and corrosion resistance.