Stainless Steel, Martensitic1.4125 (440C) Bar

A martensitic stainless steel with the highest carbon content in the 400 series.

440C stainless steel is a member of the 400 series of stainless steels. It has the highest carbon content among them. It is capable of attaining, after heat treatment, the highest strength, hardness and wear resistance of all the stainless alloys. Its very high carbon content is responsible for these characteristics, which make 440C particularly suited to such applications as ball bearings and valve parts.

Martensitic stainless steels are optimised for high hardness, and other properties are to some degree compromised. Fabrication must be by methods that allow for poor weldability and usually also allow for a final harden and temper heat treatment.

Corrosion resistance is lower than the common austenitic grades, and their useful operating temperature range is limited by their loss of ductility at sub-zero temperatures and loss of strength by over-tempering at elevated temperatures.

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Related Specifications

440C
UNS44004
1.4125

Properties

Chemical Composition

Chemical Element	% Present
Carbon (C)	0.95 - 1.20
Chromium (Cr)	16.00 - 18.00
Manganese (Mn)	0.00 - 1.00
Silicon (Si)	0.00 - 1.00
Phosphorous (P)	0.00 - 0.04
Sulphur (S)	0.00 - 0.03
Molybdenum (Mo)	0.40 - 0.80
Iron (Fe)	Balance

Mechanical Property	Value
Proof Stress	448-1900 MPa
Tensile Strength	758-2030 MPa
Elongation A50 mm	4-14 %

General Physical Properties

Physical Property	Value
Density	7.65 g/cm³
Thermal Expansion	10.1 x 10^-6/K
Modulus of Elasticity	200 GPa
Thermal Conductivity	24.2 W/m.K
Electrical Resistivity	0.6 x 10^-6 Ω .m

Applications

Rolling element bearings
Valve seats
High quality knife blades
Surgical instruments
Chisels

Characteristics

Excellent hardness
High wear resistance
Good mechanical strength
Good fatigue resistance
Moderate corrosion resistance

Additional Information

Weldability

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Disclaimer

This Data is indicative only and as such is not to be relied upon in place of the full specification. In particular, mechanical property requirements vary widely with temper, product and product dimensions. All information is based on our present knowledge and is given in good faith. No liability will be accepted by the Company in respect of any action taken by any third party in reliance thereon. Please note that the 'Datasheet Update' date shown above is no guarantee of accuracy or whether the datasheet is up to date.

The information provided in this datasheet has been drawn from various recognised sources, including EN Standards, recognised industry references (printed S online) and manufacturers' data. No guarantee is given that the information is from the latest issue of those sources or about the accuracy of those sources. Material supplied by the Company may vary significantly from this data but will conform to all relevant and applicable standards. As the products detailed may be used for a wide variety of purposes and as the Company has no control over their use; the Company specifically excludes all conditions or warranties expressed or implied by statute or otherwise as to dimensions, properties and/or fitness for any particular purpose, whether expressed or implied. Advice given by the Company to any third party is given for that party's assistance only and without liability on the part of the Company. All transactions are subject to the Company's current Conditions of Sale. The extent of the Company's liabilities to any customer is clearly set out in those Conditions; a copy of which is available on request.