4140 steel is a hardenable tool steel alloy popular for Hammers, Tomahawks, Gears, Shafts, Bolts, Crankshafts, and Piston Rods in industries from aerospace to agriculture.
4140 Tool steel is also available in 2.0" Diameter Lengths and Miscellaneous Sizes of 4140 Round Bar.
It has great versatility. 4140 is highly formable (ductile) when annealed (unhardened), yet can be hardened and tempered to a wide range of hardness, tensile, torsion, strength, impact, and abrasion characteristics.
Tougher than most carbon steels it is highly weldable before heat treating.
Though often called a ChroMoly alloy because of its chromium and molybdenum. it is also high in manganese and carbon.
Hardened 4140 can be annealed by gradually cooling after being heated to 1600°F.
4140 can be drawn into a thin wire or used for its exceptional tensile strength and hardened to withstand a loading of 95,000 psi.
4140 can also be case hardened by quenching at 1375 rather than 1575°F.
Some lengths of 4140 may be turned and polished, and others have a hot-rolled finish.