440A and 440C are high carbon martensitic stainless steels that harden to very high hardness. 440C, with the highest carbon, reaches roughly 58 to 60 HRC and is the standard stainless bearing and cutlery grade; 440A trades some hardness for improved toughness and corrosion resistance.
Chromium carbides give the wear resistance, and the same carbides limit corrosion resistance relative to the austenitic grades, so these alloys suit wear service in mildly corrosive rather than aggressive environments.
Stocked as bar, with 440F free machining available for turned parts.
Specifications
Material is released to the applicable specification with mill test reports and, on request, independent lab verification.
Why engineers specify 440-A, 440-C
- Very high hardness and wear resistance for a stainless steel
- Good dimensional stability after hardening
- Corrosion resistance well above tool steels
- 440A, 440C and free machining 440F all available
Nominal chemistry
Percent by weight, nominal composition per the governing specification. The mill test report for your heat is the controlling document.
Typical mechanical properties
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| Annealed | ~110 ksi | ~65 ksi | ~14% | ~269 HBW max |
| Hardened and tempered 440C | ~285 ksi | ~275 ksi | ~2% | 58-60 HRC |
Typical published values for reference only, not for design. Properties vary with section size, product form and processing. Order to the specification and condition your drawing requires.
Typical applications
- Bearings and races
- Valve seats and pump parts
- Cutlery and blades
- Wear components and bushings
Fabrication notes
Machining
Austenitic grades work harden quickly, so use positive rake tooling, rigid setups, generous feed and flood coolant rather than light dwelling cuts. Martensitic and precipitation hardening grades machine most easily in the annealed or solution treated condition and are aged after rough machining.
Welding
Weldable by GTAW, GMAW, resistance and electron beam methods with matching or over alloyed filler. Stabilized and low carbon grades resist sensitization in the weld zone. Precipitation hardening grades are normally welded in the solution treated condition and aged afterward.
Forming
Sheet and strip form well in the annealed condition; cold worked tempers trade formability for strength. Allow for springback and, where specified, an intermediate anneal between draws.
440-A, 440-C compared with similar grades
52100
Higher performing bearing steel without stainless corrosion resistance.
431
Lower hardness, much better corrosion resistance and toughness.
Designations and cross reference
- Material family
- Stainless Steel
- Werkstoff (W.Nr)
- 1.4109 / 1.4125
- EN designation
- X70CrMo15 / X105CrMo17
- Series
- 400 Series
Working from an obsolete, foreign or superseded designation? Send it over and we will cross reference it to a current grade and specification.
Quality, testing and traceability
Supplied with mill test reports and heat traceability, with penetrant dye, ultrasonic, chemical assay, hardness, corrosion and mechanical testing available on request.
We are AS9100D and ISO 9001:2015 registered. If our stock does not already carry the inspection your specification requires, we can quote the material with that work performed. More on our quality system
Available forms
440-A, 440-C frequently asked questions
What is 440-A, 440-C?
440A and 440C are high carbon martensitic stainless steels that harden to very high hardness. 440C, with the highest carbon, reaches roughly 58 to 60 HRC and is the standard stainless bearing and cutlery grade; 440A trades some hardness for improved toughness and corrosion resistance.
What forms is 440-A, 440-C available in?
We supply 440-A, 440-C in bar, billet, casting, extrusion, fitting, flange, foil, forging, pipe, plate, profile, rod, sheet, strip, tube, wire. Custom sizes are converted from billet, and we can provide saw cut, waterjet or near net blanks so material arrives closer to your finished part.
What is the UNS or equivalent designation for 440-A, 440-C?
440-A, 440-C is designated Werkstoff 1.4109 / 1.4125, EN X70CrMo15 / X105CrMo17. If your drawing calls out an obsolete or foreign designation we can cross reference it and confirm the equivalent before you order.
What specifications can 440-A, 440-C be supplied to?
Commonly ordered specifications include AMS 5631, AMS 5618, AMS 5630, AMS 5880, ASTM-A-580. Material is released to the specification and condition on your purchase order, with mill test reports supplied as standard.
What conditions can 440-A, 440-C be ordered in?
We can supply Annealed, Hardened and tempered 440C. If our stock is not already in the condition you need, we can quote it with the heat treatment performed before shipment.
Can you cut 440-A, 440-C to size?
Yes. Saw cutting, waterjet, laser and shearing are available, along with trepanning, gun drilling, lathe turning and CNC machining, so you can order blanks or rough machined pieces rather than full lengths.
Do you provide test reports and additional testing on 440-A, 440-C?
Every order ships with mill test reports and heat traceability. If your print calls for ultrasonic inspection, penetrant dye, magnetic particle, chemical assay, micrography, hardness or mechanical testing and our stock does not already carry it, we can quote the material with that work performed.
Can 440-A, 440-C be supplied to DFARS domestic melt requirements?
Tell us at quote stage if the order is DFARS or domestic melt restricted and we will confirm availability against that requirement before you commit.
What do you need to quote 440-A, 440-C?
Grade, form, dimensions, quantity, specification and condition, plus any testing or certification requirements and the date you need it. Send a drawing if you have one. Quotes are typically ready within 24 hours.
How does 440-A, 440-C compare with 52100?
Higher performing bearing steel without stainless corrosion resistance.