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.UCI-160 (also called HK alloy) has been the standard material used in reformer type furnaces for many years. It performs well in carburizing and nitriding gases (both oxidizing and reducing) up to 1800 F. HK was the first general-purpose alloy for ethylene pyrolysis furnaces. UCI-160 is used today in many replacement applications for furnace tubing.