321 stainless steel plates are part of the austenitic family of stainless steel. 321 is basically a 304 grade containing a stabilizer of titanium. Type 321 is a good choice for applications where heat is an issue. 321 can be used in applications up to 900°C where 304 is normally used up to 500°C.

321 SS is a titanium stabilized austenitic chromium-nickel stainless steel which was developed to provide an 18-8 type alloy with improved intergranular-corrosion resistance. This material is stabilized against chromium carbide formation by the addition of titanium. Since titanium has a stronger affinity for carbon than chromium, titanium carbide precipitates within the grains instead of forming at the grain boundaries.