Stainless Steel 440A · heat-treated state
Stainless Steel 440A Hardened & Tempered
Properties of the Hardened & Tempered condition, compared with the other 440A tempers.
General service condition for blades, valve parts and wear components.
What is 440A Hardened & Tempered?
440A Hardened & Tempered is 440A heat treated to Hardened & Tempered — general service condition for blades, valve parts and wear components. 440A Hardened & Tempered has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,790 MPa (260 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 200 GPa (29 Msi). 440A Hardened & Tempered 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). Annealed is the default condition FabDigit quotes; Hardened & Tempered is available on request or by drawing note.
Advantages
- High strength — 1,650 MPa (239 ksi), better than 100% 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 84% of stainless steel grades
Limitations
- Limited ductility — 5%, worse than 100% of stainless steel grades
- Difficult to machine — 12/100, worse than 100% of stainless steel grades
- Difficult to weld — 10/100, worse than 100% of stainless steel grades
- Limited formability — 3/100, worse than 100% of stainless steel grades
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
440A Hardened & Tempered properties
Typical room-temperature values for 440A Hardened & Tempered — 19 properties are specific to this condition; the rest are grade-level values shared by every 440A temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
440A Hardened & Tempered 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 Hardened & Tempered has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,790 MPa (260 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
440A Hardened & Tempered is rated for continuous service to 300°C (572 °F). It conducts heat at 24.2 W/m·K (14 BTU/hr·ft·°F), better than 84% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
440A Hardened & Tempered conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of 440A Hardened & Tempered takes about 55 MJ of energy and emits 5.5 kg of CO₂ — less than 51% of stainless steel grades. Typical recycled content is 45%.
Manufacturability7
440A Hardened & Tempered's machinability is not recommended (12/100, worse than 100% of stainless steel grades); weldability not recommended (10/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 440A tempers and conditions
440A is also supplied in 6 other conditions. The full side-by-side table is on the 440A overview.
- AnnealedDefaultStock condition for machining, blanking and grinding before hardening.415 MPa yield · 195 HB
- H&T 150CMaximum hardness and edge retention with best corrosion resistance; lowest toughness.1,720 MPa yield · 56 HRC
- Hardened & TemperedGeneral service condition for blades, valve parts and wear components.1,650 MPa yield · 51 HRC
- H&T 315CStandard published H&T condition — balanced hardness, strength and toughness.1,650 MPa yield · 51 HRC
- H&T 600CUse only when higher toughness or elevated-temperature stability is needed; corrosion resistance drops.1,080 MPa yield · 40 HRC
- Cold DrawnPick for close-tolerance bright bar going straight to screw-machine work.620 MPa yield · 250 HB
Working with 440A Hardened & Tempered
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.
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.
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 | — |
440A Hardened & Tempered — frequently asked
What is 440A Hardened & Tempered used for?
440A Hardened & Tempered 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 Hardened & Tempered?
440A Hardened & Tempered has a typical yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,790 MPa (260 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 440A Hardened & Tempered easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 100% 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 Hardened & Tempered be welded?
Not readily — weldability is rated not recommended (10/100). 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 Hardened & Tempered?
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 Hardened & Tempered 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 Hardened & Tempered?
440A Hardened & Tempered is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 440A Hardened & Tempered?
Yes — 440A Hardened & Tempered is available for CNC machining with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.