4140 steel is a chromium, molybdenum, manganese low alloy steel plate that is known for its toughness, high fatigue strength, and high torsional strength.


Typical Standards

Thickness (Metric/Imperial)
3" - 10"36" - 96"96" - 240"

General Info About 4140 Steel Plate

It is a low alloy steel plate that is used in many different industries.

More Details About 4140 Steel Plate

  • Advantages/Disadvantages

    4140 steel plate has high fatigue strength, excellent toughness, and good corrosion resistance. One disadvantage is the extra care that must be taken when welding it.

  • Industries

    This grade is used in the aerospace, oil and gas, and many other industries.

  • Applications

    This material is often used for shafts, crankshafts, gears, collars, and machinery parts because of its toughness, abrasion and impact resistance, and high fatigue strength.

  • Machining

    It possesses good machinability in the annealed condition.

  • Welding

    It is weldable by all conventional methods but requires preheating beforehand.

  • Heat Treatment

    It is hardened by heating to 1550°F or 845°C followed by quenching in oil.

Chemical Properties

0.8 - 1.10 0.75 - 1.00.380 - 0.4300.15 - 0.300.15 - 0.25 0.0400.035Balance

Mechanical Properties

Properties Metric Imperial
Tensile Strength 655 MPa95,000 PSI
Yield Strength 415 MPa60,200 PSI
Bulk Modulus 140 GPa20,300 KSI
Shear Modulus 80 GPa11,600 KSI
Elastic Modulus190 - 210 GPa26,557 - 30,458 KSI
Poisson's Ratio 0.27 - 0.300.37 - 0.30
Elongation at Break (50mm) 25.7%25.7%
Brinell Hardness197197
Machinability (set to AISI 1212 as 100 Machinable)6565

Frequently Asked Questions

  • Is 4140 a carbon steel?


    It is considered a low alloy or carbon steel. With the addition of chromium and molybdenum, it is one of the most common alloy steels. The chromium boosts corrosion resistance and the molybdenum boosts toughness.

  • Does 4140 rust?


    This steel plate has excellent resistance to corrosion compared to other types of steel because of its higher percentage of chromium and molybdenum. However, once the corrosion process has started, it will rust just like most steel that has undergone the same damage.

  • Can 4140 steel be welded?


    It can be welded but requires preheating beforehand because it is more crack sensitive.

  • What makes this grade a "chromoly" steel?


    The addition of chromium and molybdenum are why it is considered a “chromoly” steel.

  • What goes into the AISI 4140 designation?


    The first “4” is 4140 indicates that the steel contains molybdenum at higher levels than other steels like the 1xxx series.

    The “1” in 4140 indicates the addition of chromium at higher levels than 46xx steels.

    The “40” differentiates this steel from other 41xx series steels.

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