Stainless Steel 440F
AISI/SAE 440F · UNS S44020 · ASTM A582 · EN 1.4109, X70CrMo15 · JIS SUS440F
440F is a high-carbon Cr-Mo martensitic stainless (S44020, 1.4109, X70CrMo15, SUS440F, 7Cr17Mo) with a free-machining sulfur addition, chemically close to 440B and hardenable to high hardness.
Values for the Annealed condition
440F tempers and conditions
440F is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault subcritical/full annealed bar (default stock condition) | Stock condition for high-volume screw-machine work; parts are machined soft then hardened and tempered. | 415 | 760 | 13 | 255 HB | — |
Annealed and cold drawn bar | Pick for close-tolerance, bright-finish bar feeding CNC lathes when a slightly higher as-machined strength is acceptable. | 620 | 860 | 8 | 30 HRC | 2.9 % IACS |
Hardened and tempered ~300–370 °C for higher toughness | Use when a little more toughness and dimensional stability is needed and peak hardness/corrosion resistance can be traded away. | 1,480 | 1,650 | 5 | 50 HRC | — |
austenitize ~1010–1065 °C, oil/air quench, temper 150–200 °C (≈55–57 HRC) | Standard service condition: choose for maximum hardness, wear resistance and the best corrosion resistance this grade can offer. | 1,720 | 1,860 | 3 | 56 HRC | — |
What is 440F?
440F is a high-carbon Cr-Mo martensitic stainless (S44020, 1.4109, X70CrMo15, SUS440F, 7Cr17Mo) with a free-machining sulfur addition, chemically close to 440B and hardenable to high hardness. It is used as annealed or annealed-cold-drawn bar for volume-turned cutting and wear parts and supplied Q&T 48–52 HRC; annealed values are 415 MPa yield, 760 MPa tensile, 13% elongation and 255 HB, with machinability 55 — the best in the 440 family. The sulfide stringers cut corrosion resistance (score 32), formability (score 20) and polishability, and service is limited to 400 °C. Use 440B or 440C where corrosion resistance or a true mirror finish matters. 440F has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,370°C (2,498 °F). 440F has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi).
What is 440F used for?
- Cutlery
- Surgical instruments
- Knife blanks
Advantages
- Easy to machine — 55/100, better than 94% of stainless steel grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 91% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Conducts heat well — 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades
Limitations
- Needs corrosion protection — 32/100, worse than 99% of stainless steel grades
- Difficult to weld — 12/100, worse than 99% of stainless steel grades
- Limited ductility — 13%, worse than 93% of stainless steel grades
- Limited formability — 20/100, worse than 86% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
440F properties
Typical room-temperature values for 440F-Annealed; bars are the position among stainless steel grades.
Physical3
440F has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical15
440F has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
440F is rated for continuous service to 400°C (752 °F). It conducts heat at 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
440F conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 99% of stainless steel grades.
Sustainability4
Producing a kilogram of 440F takes about 53 MJ of energy and emits 3.4 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 40%.
Manufacturability6
440F's machinability is good (55/100, better than 94% of stainless steel grades); weldability not recommended (12/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 440F is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 440F
Is 440F easy to machine?
Best machining of the 440 family — run annealed with rigid setups, positive-rake carbide, moderate speeds and heavy soluble-oil coolant; expect abrasive wear from Cr-carbides and grind after hardening.
Can 440F be welded?
Not recommended: high carbon plus high sulfur cause hot cracking and hard, brittle HAZ; if unavoidable, preheat 200–300 °C, use 309/310 filler and anneal immediately.
Can 440F be formed, bent or molded?
Cold forming is essentially limited to light straightening; hot work 1150→900 °C followed by slow cooling and a full anneal to avoid quench cracks.
Manufacturability
The process limits FabDigit applies to 440F. Every 440F part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Excellent55 / 100 |
|---|---|
| ISO material group | M.4 |
| Cutting speed (rough / finish) | 140 / 170 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
440F chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Chigh carbon gives Cr-carbides for hardness/wear | 0.95 – 1.2 | 1.05 |
| Cr | 16 – 18 | 17 |
| Mn | ≤ 1.25 | 0.8 |
| Si | ≤ 1 | 0.5 |
| Sfree-machining addition (MnS); Se-bearing 440F Se variant substitutes ≥0.15 % Se | ≥ 0.15 | 0.2 |
| P | ≤ 0.06 | 0.03 |
| Mooptional; may be added to aid machinability/hardenability | ≤ 0.6 | 0.4 |
| Fe | balance |
What surface finishes work on 440F?
Harden, temper and passivate (nitric or citric) for usable corrosion resistance; hard chrome or electroless nickel is common for wear/corrosion duty, and sulfide stringers keep it from taking a true mirror polish.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 440F in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S44020
- ASTM
- A582
- EN / DIN / Werkstoff-Nr.
- 1.4109X70CrMo15
- JIS
- SUS440F
- Similar grades
- 440B7Cr17MoX102CrMoS17
How much does 440F cost?
440F is a standard-cost stainless steel ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
440F — frequently asked
What is 440F used for?
440F is typically used for cutlery, surgical instruments and knife blanks. In short: free-machining cutlery stainless.
What is the yield strength of 440F?
440F has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 62% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 440F easy to machine?
Reasonably — machinability is rated good (55/100, better than 94% of stainless steel grades). Best machining of the 440 family — run annealed with rigid setups, positive-rake carbide, moderate speeds and heavy soluble-oil coolant; expect abrasive wear from Cr-carbides and grind after hardening.
Can 440F be welded?
Not readily — weldability is rated not recommended (12/100). Not recommended: high carbon plus high sulfur cause hot cracking and hard, brittle HAZ; if unavoidable, preheat 200–300 °C, use 309/310 filler and anneal immediately.
What surface finishes work on 440F?
Harden, temper and passivate (nitric or citric) for usable corrosion resistance; hard chrome or electroless nickel is common for wear/corrosion duty, and sulfide stringers keep it from taking a true mirror polish.
Can 440F be formed, bent or molded?
Cold forming is essentially limited to light straightening; hot work 1150→900 °C followed by slow cooling and a full anneal to avoid quench cracks.
What is the maximum service temperature of 440F?
440F is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 440F Annealed and 440F-ACD?
Annealed is the default condition — stock condition for high-volume screw-machine work; parts are machined soft then hardened and tempered. ACD: pick for close-tolerance, bright-finish bar feeding CNC lathes when a slightly higher as-machined strength is acceptable. Yield strength is 415 MPa in Annealed versus 620 MPa in ACD.
How much does 440F cost?
440F is a standard-cost stainless steel ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 440F?
Yes — 440F is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A582/A582M — Free-Machining Stainless Steel Bars — ASTM International (2021)
- EN 10088-3 (X70CrMo15 / 1.4109 related martensitic grades) — CEN (2014)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Specialty Handbook — Stainless Steels — ASM International (1994)
- Martensitic free-machining stainless bar datasheets (440C/440F class) — Various bar producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.