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.SAE 4145 is a through-hardening, medium-carbon chromium-molybdenum alloy steel of high hardenability. It is recommended for heavy-duty service and is suitable for a wide variety of engineering uses. Its many applications include gears, axles, flanges, machine tool parts, nitrided parts, bolts, connecting rods, sprockets and valve seats.