We build a variety of custom enclosures for offshore, marine, corrosive atmosphere applications and we are asked what material is best suited for them. 5052 Aluminum is an acceptable material especially when weight of an enclosure is an issue. It will eventually show signs of surface corrosion or surface pitting after prolonged exposure to salt water/ or corrosive environments.
A common practice to reduce or minimize those effects are to anodize the enclosure. Anodization increases surface hardness, increases corrosion resistance and is non conductive. The coatings can withstand up to about 80 degrees C, prolonged exposure to high temperatures can cause cracking in the finish, but it will not peel.
The other option is to construct the enclosures out of Stainless Steel. We use both 304L and 316L grades of stainless. Both materials are suitable for corrosive environments due to their Chromium and Nickel content but they are substantially heavier than Aluminum. Of the two materials 316L stainless steel is the most corrosion resistant material for constriction, this is due to the higher Nickel content and the addition of Molybdenum. But what about hardware? Many people ask for an enclosure constructed in 316L stainless and also request all the hardware (nuts, bolts, and fasteners) be constructed from 316L stainless as well. Although 316L stainless steel is the best material for corrosion resistance on the body of the enclosure it is not the best material for hardware. 304L stainless steel has higher strength and wear resistance than 316L stainless, due in part to the slightly higher Chromium content. With higher strength and wear resistance and a lower cost than 316L hardware it is the best choice of hardware on any enclosure that will be exposed to corrosive environments. Please share your feedback or send any questions you might have about metals in corrosive environments, we love to talk metal!
