321 Stainless Steel Hex Nuts are used in different application types. 321 material is a stable austenitic stainless steel. Meanwhile, stainless steel UNS S32100 hex bolts are a moderated austenitic alloy, the same as alloy 304, but with at least 5 times more titanium than carbon. The material contains 17% chromium, 9% nickel and titanium and is stable with carbon, iron, manganese, nitrogen, phosphorus, sulfur and silicon.