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Alloy 300M/S155 is a vacuum-melted steel with outstanding strength. A through hardening alloy combining toughness, fatigue strength and good ductility.


Product Form Size range from Size range to
300M/S155 Round bar 22.23 mm 127 mm

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Chemical Analysis

C Cr Fe Mn Mo Ni P Si S V
Min 0.38 0.7 Balance 0.6 0.3 1.65 0.01 1.45 0.01 0.05
Max 0.46 0.95 Balance 0.9 0.65 2 - 1.8 - -


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Ideal for the motorsport industry

300M/S155 can be used in a variety of applications including:

  • Undercarriage components
  • Gears
  • Shafts
  • Aircraft landing gear
  • High strength bolts

About 300M/S155

300M/S155 is a high performance alloy steel which is a vacuum melted grade, supplied in the normalised and tempered/softened condition to enhance machinability prior to final heat treatment.

It has a combination of ultra high strength, good fatigue resistance and excellent transverse properties, and as such finds many applications in the aerospace industry, such as undercarriage components, gears and shafts.

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

For more information on alloy steel contact us, or fill in our online quote form and we’ll get right back to you!



7.85 g/cm^3
Specific Heat Capacity:
448 J/kg*K
Coefficient of Thermal Expansion from -17.8-93°C:
11.34 µm/mm/°C


AMS 6417, ASTM A579
Download the 300M/S155 Data Sheet Download

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