4140 annealed is an aircraft quality low-alloy steel containing chromium, molybdenum, and manganese. The chromium content provides good hardness penetration, and the molybdenum imparts uniform hardness and high strength. 4140 in the annealed condition provides good ductility before being hardened to a capability of 50 HRC. This alloy is characterized by its high fatigue strength, torsional strength, abrasion resistance, and toughness. This material is used to produce piston rods, shafts, crank shafts, gears and other machinery parts. (UNS G41400)
Element | Min | Max |
---|---|---|
Carbon, C | 0.38 | 0.43 |
Manganese, Mn | 0.75 | 1 |
Silicon, Si | 0.15 | 0.35 |
Phosphorus, P | - | 0.025 |
Sulfur, S | - | 0.025 |
Chromium, Cr | 0.8 | 1.1 |
Molybdenum, Mo | 0.15 | 0.25 |
Nickel, Ni | - | 0.25 |
Copper, Cu | - | 0.25 |
Aluminum, Al | 0.02 | 0.05 |
Vanadium, V | 0.02 | 0.08 |
Columbium/Niobium, Nb | 0.02 | 0.05 |