Alloy Grade UNS: 440C – Martensitic Stainless Steel

  • Overview

    440C is a martensitic stainless steel alloy and is one of the hardest stainless grades when fully hardened and stress relieved. This hardness, coupled with permanent carbides in the structure, makes this high-carbon alloy exceptionally resistant to abrasive wear. The chromium content provides good corrosion resistance. Before welding, it should be preheated and stress-relieved immediately after welding. It is machinable in the annealed condition and is magnetic. This 440C alloy has higher levels of carbon compared to 440A and 440B.

  • Typical Uses

    Valve components, pump parts, shaft sleeves, and bearings.

  • MetalTek Grade

    MTEK 440C

Similar Specifications

Cast UNS: J91639

Wrought UNS: S44004

Wrought Grade: 440C

Cast Grade: 440C

Military/AMS: AMS 5352

* AMS specifying investment casting.

Typical Chemical Composition (% by wt.)

Aluminum: n/a

Carbon: 0.95-1.20

Chromium: 16-18

Manganese: 1

Iron: BAL

Copper: n/a

Nickel: 0.75 MAX

Lead: n/a

Tin: n/a

Silicon: 1

Zinc: n/a

Other: Mo 0.25-0.75

Minimum Mechanical Properties

Brinell Typical:

0

Heat Treatment: Anneal

NOTES: Brinell value is MAX.

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Stainless Steel

Stainless steels owe their ability to resist corrosion primarily to the presence of a passive film on their surface. Chromium is chiefly responsible for formation of the passive film. Iron ceases to rust at approximately 12% chromium content and resistance to oxidizing corrosives increases rapidly with chromium content up to approximately 20%.
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