Alloy 321 is austenitic SS that are titanium stabilized with excellent general corrosion resistance.Alloy 321H is the high carbon version of the alloy and was created for the purpose of improvising high strength at the temperature above 537 Deg C https://www.siddhgiripiping.com/stainless-steel-321-321h-pipes-and-tubes-manufacturers-suppliers-stockists-exporters.html