What is 440C Stainless Steel?

Stainless steel 440C is a martensitic stainless steel and is supplied in round bar. After heat treatment, it’s capable of attaining the highest strength, hardness and wear resistance of all the stainless alloys.

440C is very similar to 440A and 440B but with a higher carbon content and slightly lower corrosion resistance. 440C is also more readily available.

Stainless steel 440C is relatively easily machined in the annealed condition. Carbide or ceramic tooling is recommended for use with this alloy.

Machining is extremely difficult once hardened and not recommended.

You may also see stainless 440C referred to as:

• 1.4125
• UNS44004
• AISI440C
• X105CrMo17
• Z100CD17
• X102CrMo
• 17KU
• ASTM A276
• AMS 5618 (aerospace grade)

Main attributes

• Moderate corrosion resistance in mild environments
• Excellent wear resistance and hardness
• Good strength
• Responds well to heat treatment
• Magnetic in all conditions
• Not recommended for using in elevated or sub-zero temperatures

Common Applications

• Bearings & bushings
• Valves & pumps
• Surgical & dental instruments
• Tooling & molds

Technical properties

440C Stainless Steel Physical Properties

Bar - Up to 100mm Dia / Thickness - Spec: EN 10088-3:2005

Typical chemical composition (weight %)