There are five primary subfamilies of stainless steel, yet just one of them comprises as much as two-thirds of global stainless production. Austenitic stainless grades are known for excellent thermodynamic performance; retaining a characteristic face-centered cubic (FCC) crystal structure at all temperatures. This makes austenitic grades like 316 stainless steel uniquely suited to cryogenic applications, albeit with limited formability options.

316 stainless steel is, in turn, the second most common austenitic grade behind type 304. These two are chemically similar, containing comparable levels of nickel (Ni) and chromium (Cr). Nickel enhances the low-temperature performance of stainless alloys, generally imparting good ductility to avoid brittleness in cryogenic conditions. Chromium, meanwhile, is the main element responsible for the corrosion-resistant properties of stainless steels.

The main difference between these two austenitic grades is the presence of as much as 3% molybdenum (Mo) in 316 stainless steel compared to the trace levels of type 314. This elevates the corrosion-resistant properties of the alloy even further. For example, it boasts vastly superior resistance to chloride and sulfide corrosion. So, when is 316 stainless steel more suitable than type 304?

Applications of 316 Stainless Steel

316 stainless steel is often referred to as a marine grade alloy due to its outstanding resistance to chloride corrosion. Sodium chloride (NaCl) in seawater actively attacks the iron (Fe) molecules in submerged alloys, causing pitting corrosion. The leading solution to the challenge of steel grades and seawater corrosion is to utilize increased levels of anti-corrosive elements such as molybdenum. 316 stainless steel generally outperforms type 304 in coastal and marine applications, including offshore construction and coastal architectural fascia.

Although it is now a common solution in marine applications, 316 stainless steel was originally developed for industrial processing in pulp and paper mills. Sulfur compounds in paper processing are highly corrosive, causing a similar form of mechanical pitting to chloride corrosion. The steeping of raw and pressed fiber materials also generates excessive amounts of humidity which can accelerate corrosion and cause premature mechanical failure. Each of these elements was problematic for standard stainless grades, so a novel solution with improved anti-corrosion properties was developed: 316 stainless steel.

We now see 316 stainless steel routinely diagnosed for processing and construction applications as varied as:

  • Heat exchangers;
  • Pharmaceutical equipment;
  • Food contact and processing equipment;
  • Pasteurization and fermentation tanks.

As a general rule: 316 stainless steel is better suited for applications with high amounts of corrosive elements, or where the component will be continuously submerged in water.

316 Stainless Steel from Masteel

Masteel is the UK’s leading supplier of 316 stainless steel in standard, low- and high-carbon formats. If you would like to learn more about these specialist grades, read our previous blog post: Two Grades of 316 Stainless Steel. Otherwise, contact us if you have any questions.