Stainless steel comes in several qualities.
- AISI 303 (1.4305) (Stainless Steel A1) approximately 304 but more machinable due to sulfur.
- AISI 304 (1.4301) (Stainless Steel A2) comprises of 18% chromium and 8% nickel.
- AISI 316 (EN 1.4401) (Stainless Steel A4) is 16% chromium, 10% nickel and 2% molybdenum.
- AISI 316L is the low carbon variant to enhance weldability.
For seawater 316 quality is often advised. I'd like to understand:
- By what process does molybdenum make the metal more resistant to corrosion in seawater?
- How do the material loss rates compare between these grades of stainless steel, as well as to ordinary structural steel (S235, S275 or S355)?