View Sample Alloy Digest Data Sheet (PDF)Since 1952, Alloy Digest has been the leading reference for materials property data on metals and alloys used throughout the world. Featuring graphs, charts and tables, these sheets give facts and figures on composition or characterization, physical and mechanical properties, heat treatment, and machinability.Armco 21-6-9 is an austenitic stainless steel alloy designed for use in applications where a combination of high strength and corrosion resistance is desired.