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 4137 is a medium-carbon low-alloy steel suitable for heavy-duty service. It is nominally an oil-hardening steel; however, it may be water hardened if suitable precautions are taken to avoid cracking. Its many uses include axles, fittings, gears, crankshafts and nitrided parts. It has a low tendency to develop temper embrittlement.