Stainless steel 321 shares similarities with SS 304, it is also austenitic alloy but with the abundance of five times the carbon content and addition of titanium. Due to high concentration of carbon in this steel alloy, there’s no chance of carbide precipitation during welding. Alloy 321 offers excellent immunity to corrosion and oxidation. SS 321 is amazing with its mechanical properties and therefore can be used in high temperature environments. In comparison to SS 304, alloy 321 is more suitable to resist creep and stress rupture. The presence of high nickel and chromium makes this alloy excellent for overall corrosion resistance.
SS 321H is the version of alloy 321 with 0.04 – 0.10 higher carbon content. This alloy was particularly formed to achieve improved creep resistance and for better strength, so that it could be used in temperatures as high as 10000 F (i.e. 537° C). It has been observed that in most processes, the carbon component of this alloy allows dual certification.