304 or 316 Stainless Steel: What’s the difference?
Mixer and tank manufacturers commonly standardize on stainless steel grades for their products based on the industries and applications they serve. The term “stainless steel” refers to a wide range of steels that resist rust, corrosion and discoloration due to the presence of at least 10.5% chromium in the alloy. What they all have in common is that the chromium forms a protective layer of chrome-oxide on the material surface. It is this layer that prevents rust and corrosion from forming and entering the molecular structure of the material and protects the iron.
Type 304 stainless steel is the most commonly used of the popular 300-series of alloys. It consists of 18% chromium, 8% nickel and a maximum of 8% carbon and offers very good resistance to rust and corrosion. For this reason, it is common in industries such as food production equipment. However, there are many applications and chemicals across all industries that call for a higher level of protection. Grade 316 stainless steel provides increased resistance to corrosion due to nickel in its formulation that is further enhanced by the addition of 2% molybdenum. This additional protection makes 316 the alloy on which most mixer manufacturers standardize.
INDCO engineers can assist you with material selection for your application including those rare instances when 316 stainless steel is insufficient. In these applications, Hastelloy C276 is our most frequently used alternative.