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. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SA-366. Producer or source: Alloy steel mills and foundries.