Stainless Steel 440C

Your guide to 440C Stainless Steel Machining



A martensitic stainless steel

Supplied in round bar

Excellent wear resistance and hardness

440C stainless is capable of attaining the highest strength, hardness and wear resistance of all the stainless alloys after heat treatment. It is relatively easily machined in the annealed condition but machining after heat treatment is not recommended.

This guide will take you through the main attributes, common applications, notes for designers and suitable finishing and treatments, as well as UK stock sizes and property tables. Don't forget to bookmark the page so you can refer back later.

If you are interested in stainless 440C machined parts, please scroll to the bottom of the page for more information about our service and to request a quote.

440C Guide: Properties, Applications and Design Considerations


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)

Industry Examples: Medical | Automotive


Typical Components & Applications: Ball bearings | Valve parts | Rolling element bearings | Surgical instruments | Measuring instruments | Nozzles | Gage blocks | Mould inserts | Bushings

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
Can we meet your stainless steel 440C machining needs? Contact us now
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Further Reading & Resources

British Stainless Steel Association


440C Machining Stainless Steel Machined Parts


Penta Precision provides the following 440C machining services: 
  • CNC milling
  • CNC turning
  • Prototypes and batch runs
  • Insert installation
  • Part marking
  • Manual milling
  • Manual turning
  • Machining design advice
  • Design for manufacture service

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