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4140 Alloy Steel Round Bar - Alloy Steel

4140 Alloy Steel Round Bar - Alloy Steel


4140 Alloy Steel Round, is an cold drawn annealed steel of relatively high hardenability with its chromium content provides good hardness penetration, and the molybdenum imparts uniformity of hardness and high strength. It is a Medium-carbon steel with high hardenability and good fatigue, abrasion and impact resistance. 4140 Alloy Steel Round responds well to heat-treatment and is relatively easy to machine in the annealed condition. 4140 Alloy Steel Round has good strength and wear resistance, excellent toughness, coupled with good ductility, and the ability to resist stress at elevated temperatures.

4140 is a chromium and molybdenum alloy steel that has an excellent weight to strength ratio. It is considerably stronger than standard steel. Although it is chromium steel and often referred to as "chromoly steel", it does not contain as much chromium as stainless steel. Therefore the corrosion resistant is improved compared to standard steel but not to the same degree as stainless steels. 4140 responds readily to heat treatment and is relatively easy to machine in the heat treated condition.

4140 is an oil-hardening steel that can maintain its properties even after long exposure to relatively high working temperatures. A broad range of strength and toughness is attainable through variations in heat treatment. These grades are particularly suitable for forging because they have self-scaling characteristics.

4140 Alloy Steel Round Bar is noted for its toughness, good torsional strength and good fatigue strength. Machinability of this alloy is good in the annealed condition. In the heat treated and quenched condition machining is best limited to finish grinding. These alloys have good ductility, but are tougher than plain carbon steel and thus usually require more force, or pressure, for forming. 4140 Alloy Steel is weldable by all of the conventional methods. Note that welding with the alloy in the heat treated condition will affect the mechanical properties and a post weld heat treatment may be needed.

  • Specifications: ASTM A331, AISI 4140
  • AKA: CDA Alloy Round, Alloy steel shaft
  • Applications: shafts, axels, bolts, sprockets, piston rods, rams, etc. 
  • Workability: Moderate to Weld, Cut and Machine.
  • Mechanical Properties: Brinell = 223, Tensile = 102,000 +/-,  Yield = 90,000 +/-


Alloy 4140 is typically used in the Oil and Gas industry, applications such as gears, pumps and drills. This strong alloy is used for its good hardness penetration and hardness uniformity. Its high machinability and ability to maintain its properties at high temperatures make this alloy useful in many industries. Typical applications include Arbors, Axle Shafts, Bolts, Crankshafts, Connection Rods, Chuck Bodies, Collets, Ejector Pins, Forks, Gears, Guide Rods, Hydraulic Shafts & Parts, Lathe Spindles, Milling Spindles, Motor Shafts, Pinions, Pump Shafts, Spindles, Sprockets, Studs, Tool Holders and Torsion Bars. 4140 is a widely used general purpose grade of alloy steel. It offers a wide range of highly desirable properties such as good strength and hardenability, wear resistance, toughness and good ductility.

 4140 Alloy Steel Round Bar Pictures




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