Stainless Steel 440A
AISI/SAE 440A · UNS S44002 · EN 1.4109 · JIS SUS440A · GB 68Cr17, 7Cr17
440A is a high-carbon, high-chromium martensitic stainless steel (about 0.65% C, 17% Cr) covered by UNS S44002 and SUS440A, reaching 50–56 HRC after hardening and tempering.
Values for the Annealed condition
440A tempers and conditions
440A is supplied in 7 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault full/subcritical annealed, soft machinable condition | Stock condition for machining, blanking and grinding before hardening. | 415 | 725 | 20 | 195 HB | — |
annealed then cold-drawn/turned-ground-polished bar | Pick for close-tolerance bright bar going straight to screw-machine work. | 620 | 830 | 12 | 24 HRC | 2.9 % IACS |
quenched and high-temperature tempered (~40 HRC) | Use only when higher toughness or elevated-temperature stability is needed; corrosion resistance drops. | 1,080 | 1,280 | 9 | 40 HRC | — |
quenched and tempered, typical service condition (~50–52 HRC) | General service condition for blades, valve parts and wear components. | 1,650 | 1,790 | 5 | 51 HRC | — |
quenched and tempered at 315 °C (~51 HRC) | Standard published H&T condition — balanced hardness, strength and toughness. | 1,650 | 1,790 | 5 | 51 HRC | — |
quenched and low-temperature tempered (~55–56 HRC) | Maximum hardness and edge retention with best corrosion resistance; lowest toughness. | 1,720 | 1,860 | 4 | 56 HRC | — |
austenitized 1010–1065 °C, quenched, untempered | As-quenched maximum hardness; must be tempered promptly to avoid cracking. | 1,900 | 2,000 | 1 | 57 HRC | 2.7 % IACS |
What is 440A?
440A is a high-carbon, high-chromium martensitic stainless steel (about 0.65% C, 17% Cr) covered by UNS S44002 and SUS440A, reaching 50–56 HRC after hardening and tempering. Its lower carbon than 440C gives slightly better toughness and corrosion resistance at somewhat lower hardness, and it is stocked as bar, strip and plate for cutlery, shear blades, valve parts, bearing races and surgical instruments. Weldability is poor, corrosion resistance drops in the annealed condition and chlorides cause pitting. Tempering must avoid the 425–565 °C embrittlement range; use 440C when maximum hardness is required. 440A has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,370°C (2,498 °F). 440A has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
What is 440A used for?
- Diving and utility knife blades
- Cutlery blades
- Shear and slitting blades
- Valve components and seats
- Bearing races
- Surgical and medical instruments
- Wear-resistant machine parts
Advantages
- 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
- Difficult to weld — 20/100, worse than 95% of stainless steel grades
- Needs corrosion protection — 48/100, worse than 80% of stainless steel grades
- Limited ductility — 20%, worse than 79% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
440A properties
Typical room-temperature values for 440A-Annealed; bars are the position among stainless steel grades.
Physical3
440A has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical14
440A has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
440A is rated for continuous service to 760°C (1,400 °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
440A conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of 440A takes about 55 MJ of energy and emits 5.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 45%.
Manufacturability7
440A's machinability is fair (40/100, better than 72% of stainless steel grades); weldability poor (20/100); formability poor (30/100).
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. 440A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 440A
Is 440A easy to machine?
Machine only in the annealed condition with sharp, rigid, positive-rake carbide tooling and heavy coolant; hardened parts require grinding or EDM.
Can 440A be welded?
Poor weldability — preheat 200–315 °C, use matching or austenitic filler, and temper/anneal immediately after welding to avoid cracking.
Can 440A be formed, bent or molded?
Limited cold forming in the annealed state (simple bends with generous radii); hot work 1050–1150 °C and cool slowly to prevent cracking.
Manufacturability
The process limits FabDigit applies to 440A. Every 440A part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair40 / 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 |
440A 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 for martensite + Cr carbides | 0.6 – 0.75 | 0.68 |
| Cr | 16 – 18 | 17 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 1 | 0.4 |
| Mooptional | ≤ 0.75 | 0.3 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 440A?
Passivate (citric or nitric per ASTM A967) after hardening for full corrosion resistance; takes a fine mirror polish, and hard chrome or black oxide are common wear/cosmetic options.
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 440A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S44002
- EN / DIN / Werkstoff-Nr.
- 1.4109
- GB (China)
- 68Cr177Cr17
- JIS
- SUS440A
How much does 440A cost?
440A is a high-cost stainless steel ($$$$), cheaper than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
440A — frequently asked
What is 440A used for?
440A is typically used for diving and utility knife blades, cutlery blades, shear and slitting blades, valve components and seats, bearing races and surgical and medical instruments. In short: tough cutting stainless.
What is the yield strength of 440A?
440A has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 62% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 440A easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Machine only in the annealed condition with sharp, rigid, positive-rake carbide tooling and heavy coolant; hardened parts require grinding or EDM.
Can 440A be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — preheat 200–315 °C, use matching or austenitic filler, and temper/anneal immediately after welding to avoid cracking.
What surface finishes work on 440A?
Passivate (citric or nitric per ASTM A967) after hardening for full corrosion resistance; takes a fine mirror polish, and hard chrome or black oxide are common wear/cosmetic options.
Can 440A be formed, bent or molded?
Limited cold forming in the annealed state (simple bends with generous radii); hot work 1050–1150 °C and cool slowly to prevent cracking.
What is the maximum service temperature of 440A?
440A is rated for continuous use to about 760°C (1,400 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 440A cost?
440A is a high-cost stainless steel ($$$$), cheaper than about 58% 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 440A?
Yes — 440A 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 A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
- JIS G 4303 — Stainless Steel Bars (SUS440A) — JSA (2021)
- EN 10088-3 (X70CrMo15, 1.4109) — CEN (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- 440A/440B/440C Stainless Steel Product Data Sheet — AK Steel / Cleveland-Cliffs (2016)
- GB/T 1220 (9Cr18) — SAC (2007)
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.