Steel Grade AISI 4140

This medium carbon alloy grade is widely used for many general-purpose parts requiring high tensile strength and toughness. 4140 contains chromium and molybdenum as alloying elements and may be heat treated over a wide range to give the combined advantages of proper hardness, strength and ductility. In conditions where localized hardness may be required, this steel is readily flame or induction hardened.

Heat Treated, Stress Relieved (HTSR)

4140 has been heat treated to reduce brittleness and relieve any stress fractures throughout the bar. This is done by heating the material just below a specific recrystallization temperature and held there for a fixed amount of time.

Hot Roll Annealed

4140 has been annealed for increased machinability, and for better cold working. The material is placed in a large oven, then heated to it’s recrystallization temperature to repair any defects in the steel. It is then cooled very slowly inside the oven.

 American Specifications



Shafts, Gears, Nuts, Bolts, Conveyor rolls, Piston Rod

 TG&P Applications

Pump Shafts, High-Speed Motor Shafts, Axle Shafts

 Typical Chemical Analysis

Carbon 0.38 - 0.43%
Manganese 0.75 - 1.00%
Phosphorous 0.035% max
Sulfur 0.040% max
Silicon 0.15 - 0.35%
Molybdenum 0.15 - 0.25%
Chromium 0.80 - 1.10%

 Typical Mechanical Properties

Tensile Strength (ksi) 137
Yield Strength (ksi) 115
Elongation (% in 2") 21
Brinell 315
Rockwell C33, A66
* Mechanical properties for HTSR * Annealed material not tested for mechanical properties

 TG&P Size Tolerance

1-1/2” & Under +0.000” -0.001”
Over 1-1/2” – Under 2-1/2” +0.000” -0.0015”
2-1/2” – 3” +0.000” -0.002”
Over 3” – 4” +0.000” -0.003”
Over 4” – 6” +0.000” -0.006”

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