4340 Alloys Round Bar Stock

4340 Alloys has high fatigue resistance that is why it is widely used around the globe.

4340 Alloys

4340 is a nickel-chromium-molybdenum alloy steel that is characterized by its toughness and the ability to undergo heat treatment to achieve high strengths.

Because of its high fatigue resistance, it is widely used around the globe. Also, 4340 alloy steel is a medium carbon, and it has relatively large sections compared to other steels. 4340 is a type of nickel-chromium-molybdenum steel that is also known by the designation AISI 4340.

O'Hare 4340 Alloys Round Bar Stock

O’Hare Precision Metals can provide a wide range of company-supplied or customer-supplied components and materials. Just like how we can offer you the best 4340 Alloys bar stocks and 4340 Alloys round bar stocks in O’Hare!

Machinability and other Processes

4340 material is frequently used in situations where other alloy steels lack the hardenability necessary to provide the required strength. It is an excellent choice for parts that are subjected to high levels of stress. All conventional methods of machining 4340 alloy steel are also applicable.

4340 alloy steel is typically supplied hardened and tempered in the 930 – 1080 Mpa tensile range, depending on the specific application. Moreover, when hardened, the 4340 steel exhibits excellent shock and impact resistance, as well as wear and abrasion resistance.

When this steel has been pre-hardened and tempered, it can be further surface hardened by flame or induction hardening, as well as by nitriding. The ductility of 4340 steel alloy is excellent in the annealed condition, allowing it to be bent or formed with little difficulty. Our 4340 alloy steel can also be used for fusion and resistance welding applications.


Aircraft parts, gun parts, automotive parts are just a few of the many applications of 4340 Alloys.



Melting Range 

Specific Heat Capacity 

Electrical Resistivity 

7.85 g/cm^3


448 J/kg*K

1.09 µΩ.m

Chemical Properties








Sulfur 0.040

Carbon 0.38 – 0.43

0.7 – 0.9

0.6 – 0.8

0.2 – 0.3

1.65 – 2.0


0.15 – 0.3


Want to know more about 4340 Alloys? Just contact our highly skilled personnel in O’Hare Precision Metals. They are dedicated to providing smooth-flow service. Request a quote for 4340 Alloys bar stocks now!