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4340 Alloy Steel

An iron-based alloy steel, 4340 contains nickel, chromium and molybdenum

4340 Alloy Steel can be heat treated to achieve high strength whilst maintaining good toughness, wear resistance and fatigue strength levels, combined with strength up to 315 ºC.


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4340 Round bar30 mm160 mm

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Perfect for applications in the Aerospace industry

4340 Alloy Steel can be used in a variety of applications, here are just a few examples:

  • Commercial and military aircraft
  • Automotive systems
  • Forged hydraulic systems

About 4340 Alloy Steel

4340 Alloy Steel is an iron-based alloy containing nickel, chromium and molybdenum. The relatively high carbon content provides this alloy with superior strength in applications where severe service conditions exist.

4340 Alloy Steel has high strength, superior toughness and good ductility. In addition, the alloy is immune to embrittlement.


To learn more about 4340 Alloy Steel contact us today, or fill in our online quote form and we’ll get right back to you!


7.85 g/cm^3
Melting Range:
Specific Heat Capacity:
448 J/kg*K
Electrical Resistivity:
1.09 µΩ.m
Coefficient of Thermal Expansion from -18-93°C:
11.3 µm/mm/°C
Coefficient of Thermal Expansion from -18-649°C:
14.6 µm/mm/°C


AMS 6409, 6415, 2304
Download the 4340 Alloy Steel Data Sheet Download

FAQs & Resources

Alloy steels are any kind of steel to which one or more alloying elements have been added to produce a desired characteristic or physical property e.g. heat resistant, corrosion resistant etc. Common elements that are added to make alloy steel are molybdenum, manganese, nickel, silicon, boron, chromium, and vanadium.

Depending on the grades or added alloying elements, alloy steels can be found in high temperature applications, corrosive environment, high strength components, rotating parts and more. Some of the common components made of 300M/S155 and 4340 Alloy Steel are gears, shafts, aircraft landing gear, high strength bolts and forged hydraulic systems.

You can download our current approvals from our quality page.

This can vary according to the products and specification of your order. Please let us know when you need the goods and we will aim to deliver according to your requirements.

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Fill in our online form to get a fast quote. Got a technical question? Contact us on techsales@neonickel.com or for more general enquiries please email us at enquiries@neonickel.com