Choosing the Right Stainless Steel for Boat Hardware
Saltwater is one of the toughest environments for metal. Boat hardware - cleats, deck fillers, shackles, rail fittings and thru-hulls - must resist pitting and crevice corrosion for decades. The two most common choices are 316L and duplex 2205. This guide helps boatbuilders and marine suppliers decide which fits their application.
316L - The Proven Marine Standard
316L stainless steel contains molybdenum, which gives it strong resistance to chloride attack. It is the most widely used grade for marine hardware, offering good corrosion resistance, easy machining and predictable performance. For most coastal and offshore boat fittings, 316L is the safe, cost-effective choice. Best for: deck hardware, cleats, hinges, filler caps, general boat fittings.
Duplex 2205 - Higher Strength for Demanding Loads
Duplex 2205 offers about twice the yield strength of 316L plus superior resistance to stress corrosion cracking. For structural fittings that carry heavy loads - winch bases, chain plates, high-load brackets - 2205 allows lighter, stronger designs. Best for: structural hardware, high-load fittings, areas with permanent seawater immersion.
When to Choose Which
Standard deck hardware in normal coastal use → 316L
Load-bearing or safety-critical fittings → 2205
Long-term immersion or aggressive chlorides → 2205 or super duplex 2507
Cost-sensitive projects in milder environments → 304 (less common for marine)
Surface Finish and Protection
Regardless of grade, proper surface finish extends service life. A smooth, polished or electropolished surface reduces the chance of pitting. Passivation removes free iron and restores the protective oxide layer after machining.
FAQ
Can you cast boat hardware in both 316L and duplex 2205? Yes. We produce investment castings in 316L, duplex 2205, super duplex 2507 and other stainless steel grades, from customer drawings or samples.
Do you provide material certificates for marine castings? Yes, material test certificates with chemical composition and mechanical properties are provided with each shipment.
Need hardware for your boat project? Send your drawings to sales@wdshunye.com - our engineers will confirm the grade and review within 48 hours.