What is Marine Grade Stainless Steel?

Blog | October 26th, 2018

Stainless steel alloys are corrosion resistant, which means they don’t oxidize readily. However, there’s a world of difference between an alloy that’s rust resistant and one that’s rustproof. And, certainly in marine grade stainless steel, the word “resistant” just isn’t enough to assure a long and functional lifespan. Coming to the rescue, marine grade stainless steel saves the day.

Stopping Watery Oxidization 

This is an effect that has plagued shipbuilders for over a century. Simply put, water combines with iron molecules way too easily. The iron oxidizes, it rusts and breaks down. Salty environments just aggravate the effect. Stainless steel fittings do feature a natural corrosion resistant build, with chromium oxide performing as an oxidization barrier, but, in time, the water and air will have their way. A scratch, which damages the chromium coating, can also expose the underlying steel and its ferrous base. What’s required here is an alloy that won’t corrode, not if it’s scratched and not even when years of oxidizing time have flown past.

Marine-Grade Stainless Steel 

Using Stainless steel grade 316L to illustrate an important case study, the test begins. There’s electrochemical oxidization all around the metal. Salt in the air is acting as an electrolyte. The chlorine even shifts the pH of the water to make it more corrosive. Attached to some of the stainless steel parts, aquatic lifeforms, long dead, of course, have leveraged their oxidizing agents. Somehow, because this is marine grade stainless steel, the metal parts are completely unaffected. Boat fittings remain clean and whole, galley furnishings are retaining their polished good looks, and the 316L steel is performing beautifully as a corrosion proof alloy. But what’s the difference? What makes marine grade stainless steel so tough on the open seas?

Intelligently Added Alloying Elements 

A special mix of metals and alloying elements reinforces the ferrous-heavy core. There’s Molybdenum protecting the stainless steel cabinetry in the galley. The percentage of Chromium in the mix still exceeds 10.5%, but now there’s also 3% of Molybdenum in the blend. Because of this rustproof build, 316L stainless steel is commonly used in seaside restaurants as a kitchen protecting alloy. Offshore, where the alloys are submerged and continually in contact with oxygen and chlorine-rich waters, ship designers opt instead for fully corrosion proof duplex steels and austenitic heavy steels.

Milling facilities and heat treatment factories produce marine grade stainless steel. Sourced as a seaside kitchen restaurant material, the metal won’t rust, because it’s reinforced by Molybdenum. Out on the waves, 316L series steel also protects yacht galleys and dining rooms. It’s only when the metal is constantly exposed to churning waters that heavier material solutions are sought out.

Stecor Engineering & Fabrication

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