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.AISI No. 634 is a transformation and precipitation hardening stainless steel. It is used for applications such as pressure vessels, aircraft constructural components and jet engine compressor components.