440C Stainless Steel Plate - UNS S44004

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Type 440C (UNS S44004) is a martensitic stainless steel with high carbon and chromium content.  After heat treatment, it is capable of attaining the highest strength, hardness and wear resistance of all stainless alloys.  440C stainless steel derives its corrosion resistance from the inclusion of chromium, and is comparable to grade 304.  Highest resistance can be achieved through hardening and polishing, and the properties of 440C steel make it ideal for knives and cutting instruments like surgical blades. Once hardened, this material holds a sharp edge and resists corrosion, and it can be polished to a near mirror finish.  Its toughness and ability to resist wear makes 440C stainless steel a good choice for tools like chisels and ball bearings.  We sell 440C stainless steel plate products in various thicknesses. Please contact us if you have any questions about our inventory or processing and cutting services for this material.

440C Inventory Size Ranges


0.1875" - 2.500"

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Working with 440C stainless

This grade of stainless steel plate can be hardened through heat treatment, but machining is preferable in the annealed condition and becomes extremely difficult once hardened.  Recommend carbide or ceramic tooling, and chips are tough and stringy, requiring chip breakers to improve chip control and reduce cutting resistance.  440C is not usually welded due to its tendency to air harden, resulting in cracking - if welding is required, pre-heat to 250°C and follow with a post weld annealing and slow furnace cooling to prevent cracking. 

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Standard Inventory Specifications

  • UNS S44004
  • AMS 5630 Chem Only
  • ASTM: A480

Other industry standards we comply with:

  • DFARS Compliant

Common Trade Names

  • 440C Surgical Steel Plate

Common Applications of 440C

  • Cutting Instruments
  • Knife Blades
  • Surgical Instruments
  • Chisels
  • Measuring instruments
  • Ball Bearings and Valves


  • Hardenable chromium steel
  • High strength
  • High wear resistance
Chemical Properties of 440C Stainless Steel
Element Percent by Weight
C Carbon 1.20%
Cr Chromium 18%
Mn Manganese 1%
Mo Molybdenum 0.75
P Phosphorous 0.04
Si Silicon 1%
S Sulfur 0.030%

Physical Properties of 440C Stainless Steel



Density kg/mᶟ


Thermal Conductivity at 212°F (100°C)


Thermal Conductivity at 932°F (500°C)


Electrical Resistivity


Elastic Modulus (Gpa)


Mechanical Properties


Yield Strength 0.2% Proof (Mpa)


Tensile Strength (Mpa)


Elongation (% in 50mm)


Hardness (HB)

269 max



*The technical data provided is for information only and not for design purposes. It is not warranted or guaranteed.