Types of Marine-Grade Stainless Steel | 304-Grade vs. 316-Grade

Types of Marine-Grade Stainless Steel

When purchasing stainless-steel accessories for your boat, you want something that will last. Saltwater and even freshwater take their toll on just about anything made of metal. Plus, if your vessel isn't in a covered slip, the weather can also harm your hardware and accessories – if they aren’t made of quality stainless steel.

What Is 304-Grade Stainless Steel?

304-grade stainless steel is made of 18 percent chromium and 8 percent nickel. It doesn't have the corrosion-resistant molybdenum to decrease the speed of rust from de-icing salt and seawater.

Commonly used applications for grade 304 stainless steel include wheel covers, electrical enclosures, auto trim and moldings, storage tanks, kitchen appliances, and equipment that is not around saltwater, chloride, or strong disinfecting agents.

What Is 316-Grade Stainless Steel?

Grade 316 stainless steel contains 16 percent chromium, 10 percent nickel, and 2 percent molybdenum. The molybdenum significantly reduces corrosion from the salt in de-icing chemicals and saltwater. Grade 316 stainless steel also resists pitting and corrosion from spilled acidic drinks, such as soda, and cleaning materials containing chlorine and other harmful chemicals.

You can sometimes get away with using 304-grade stainless steel, which is more affordable. However, if you are boating, even on freshwater lakes and rivers, you'll want to use marine-grade 316 stainless steel. You may pay a little more upfront, but in the long run, you'll save money since you won't have to replace your hardware or accessories as frequently.

In addition to marine parts and accessories, manufacturers use grade 316 stainless steel for pharmaceutical equipment, stainless-steel baskets, chemical equipment, medical/surgical instruments, and outdoor electrical enclosures.

How to Tell the Difference Between Grade 316 and Grade 304 Stainless Steel

You can't tell the difference between 316-grade and 304-grade stainless steel by simply looking at it. However, if you have something made from 304-grade stainless steel and another item made from 316-grade stainless steel, you'll likely notice that the former rusts faster. Otherwise, you'll need a material test to determine the difference.

Marine applications and chemical processing plants use grade 316 stainless steel because it is less resistant to corrosion. This type of stainless steel also costs more because of its nickel and molybdenum composition. Therefore, if you see an accessory you want for your boat, don't go with the cheaper version – it might not be marine grade 316 stainless steel.

Another difference is that 304-grade stainless steel has a higher melting point than 316-grade stainless steel. Still, it doesn't resist chlorides and chemicals as well as marine grade 316 stainless steel does.

Often, the manufacturer will mark the stainless-steel part to indicate its grade. It might have a circle with the number 6 in it or some other marking to denote that the product you are buying is made of grade 316 stainless steel.

Benefits of Using Grade 316 Stainless Steel

The top benefits of using 316-grade stainless steel include its corrosion resistance and lasting durability for marine applications. Stainless steel will eventually pit when water (especially saltwater) hits it. However, salt from seawater will have a harder time disintegrating the coating on 316-grade stainless steel than it would on 304-grade products. Even salt air can cause pitting in Grade 304 stainless steel because it has less nickel and no molybdenum.

Visit Gemlux for Marine-Grade Stainless-Steel Boating Accessories

When you want quality accessories that will last, whether for a freshwater or saltwater vessel, visit Gemlux. We use premium 316 marine-grade stainless steel to manufacture our products, including deck hardware and accessories. 

>Contact us today to learn more or browse our inventory to find your perfect match.