When choosing the right stainless steel for a project, it is important to consider cost, strength requirements, environmental conditions, surface finish desired, and corrosion resistance. 316 stainless steel has an added element of molybdenum, which helps it resist chlorides better than other 300-series grades. This makes it the alloy of choice for many industrial applications involving processing chemicals as well as high-saline environments like coastal regions and outdoor areas where de-icing salts are used.
316 stainless steel is an austenitic, corrosion-resistant alloy, which means it has high levels of chromium and nickel with low amounts of carbon. It is also strong and tough, with good formability. It is typically welded using the GTAW/TIG, GMAW/MIG/MAG, MMAW/stick, or SAW welding methods. These processes provide excellent weldability without the need for preheating or post-weld heat treatment to maintain its corrosion resistance and strength.
While 316 is very similar to the more popular 304 grade, it contains higher levels of nickel and between 2 and 3% molybdenum. This increased level of molybdenum provides superior corrosion resistance to chlorides, making it the preferred choice for marine or coastal environments. It can handle higher temperatures than 304, as well.
The high molybdenum content of 316 also enhances its resistance to pitting corrosion, which is a localized form of corrosion that forms shallow holes in the metal’s surface. Pitting corrosion is typically caused by solutions containing chloride ions, such as seawater. 316 can be annealed to improve its resistance to pitting corrosion in these environments as well.
