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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.


Product form Size range from Size range to
4340 Round bar 30 mm 160 mm

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    Round Bar

Chemical Analysis

% Fe Ni Cr Mn C Mo Si S P
Min 95.195 1.65 0.70 0.60 0.37 0.20 0.15 - -
Max 96.33 2 0.90 0.80 0.43 0.30 0.30 0.04 0.035


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Perfect for applications in the Aerospace industry

4340 Alloy Steel can be used in a variety of applications including:

  • 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

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