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Stainless Steel 440F · supply condition

Stainless Steel 440F-ACD

Properties of the ACD condition, compared with the other 440F tempers.

Pick for close-tolerance, bright-finish bar feeding CNC lathes when a slightly higher as-machined strength is acceptable.

CNC machiningStandard cost $$
Request a quote in 440F-ACD440F overview

What is 440F-ACD?

440F-ACD is 440F supplied in the ACD condition — pick for close-tolerance, bright-finish bar feeding CNC lathes when a slightly higher as-machined strength is acceptable. 440F-ACD has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi). 440F-ACD 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). Annealed is the default condition FabDigit quotes; ACD is available on request or by drawing note.

Advantages

  • Easy to machine — 57/100, better than 97% of stainless steel grades
  • Low embodied carbon — 3.4 kg CO₂/kg, better than 91% of stainless steel grades
  • High strength — 620 MPa (89.9 ksi), better than 88% 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 — 8%, worse than 99% of stainless steel grades
  • 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 formability — 12/100, worse than 93% of stainless steel grades
  • Hard to polish — 60/100, worse than 80% of stainless steel grades

440F-ACD properties

Typical room-temperature values for 440F-ACD — 9 properties are specific to this condition; the rest are grade-level values shared by every 440F temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.

Physical3

440F-ACD 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).

Density7.7 g/cm³0.28 lb/in³
Melting Point (Solidus)1,370°C2,498 °F
Liquidus Temperature1,425°C2,597 °F

Mechanical15

440F-ACD has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 88% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi).

Elastic (Young's) Modulus200 GPa29 Msi
Shear Modulus77 GPa11.2 Msi
Bulk Modulus160 GPa23.2 Msi
Poisson's Ratio0.28
Tensile Strength (Ultimate)860 MPa125 ksi
Yield Strength (0.2% offset)620 MPa89.9 ksi
Elongation at Break8%
Reduction in Area25%
Compressive Strength430 MPa62.4 ksi
Shear Strength470 MPa68.2 ksi
Fatigue Strength (Endurance Limit)370 MPa53.7 ksi
Charpy V-Notch Impact (RT)14 J10.3 ft·lbf
Hardness, Brinell285 HB
Hardness, Rockwell B99 HRB
Hardness, Vickers265 HV

Thermal6

440F-ACD 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 84% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).

Thermal Conductivity24.2 W/m·K14 BTU/hr·ft·°F
Specific Heat Capacity460 J/kg·K0.11 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)10.2 µm/m·K5.7 µin/in·°F
Latent Heat of Fusion270 J/g116 BTU/lb
Max Service Temperature (continuous)400°C752 °F
Min Service Temperature-30°C-22 °F

Electrical3

440F-ACD conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.

Electrical Conductivity2.9 % IACS
Electrical Resistivity6×10⁻⁷ Ω·m23.6 µΩ·in
Magnetic Responseferromagnetic

Chemical & Environmental3

Corrosion resistance is poor (32/100), worse than 99% of stainless steel grades.

Galvanic Potential (seawater, vs SCE)-0.25 V
Corrosion ResistancePoor32/100
Chemical Resistance SummaryAdequate in fresh water, mild atmospheres, petroleum products, alcohols and dilute organic acids when fully hardened and passivated; attacked by chlorides, seawater, acids and steam, and the MnS stringers act as pitting initiation sites, so it is clearly inferior to 440C and to austenitic 304/316.

Sustainability4

Producing a kilogram of 440F-ACD 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%.

Embodied Energy (primary production)53 MJ/kg22,786 BTU/lb
Embodied Carbon (primary production)3.4 kg CO₂/kg
Embodied Water90 L/kg10.8 gal/lb
Typical Recycled Content40%

Manufacturability6

440F-ACD's machinability is good (57/100, better than 97% of stainless steel grades); weldability not recommended (12/100); formability not recommended (12/100).

MachinabilityGood57/100
Machinability Rating (AISI 1212 = 100 %)55%
WeldabilityNot recommended12/100
Formability (cold)Not recommended12/100
Brazeability / SolderabilityFair40/100
PolishabilityGood60/100

Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.

Other 440F tempers and conditions

440F is also supplied in 3 other conditions. The full side-by-side table is on the 440F overview.

Working with 440F-ACD

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.

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.

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.

ElementSpec limit (wt %)Nominal
Chigh carbon gives Cr-carbides for hardness/wear0.95 – 1.21.05
Cr16 – 1817
Mn≤ 1.250.8
Si≤ 10.5
Sfree-machining addition (MnS); Se-bearing 440F Se variant substitutes ≥0.15 % Se≥ 0.150.2
P≤ 0.060.03
Mooptional; may be added to aid machinability/hardenability≤ 0.60.4
Febalance—

440F-ACD — frequently asked

What is 440F-ACD used for?

440F-ACD is typically used for cutlery, surgical instruments and knife blanks. In short: free-machining cutlery stainless.

What is the yield strength of 440F-ACD?

440F-ACD has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 88% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.

Is 440F-ACD easy to machine?

Reasonably — machinability is rated good (57/100, better than 97% 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-ACD 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-ACD?

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-ACD 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-ACD?

440F-ACD 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.

Can FabDigit make parts in 440F-ACD?

Yes — 440F-ACD is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.

Sources

  1. ASTM A582/A582M — Free-Machining Stainless Steel Bars — ASTM International (2021)
  2. EN 10088-3 (X70CrMo15 / 1.4109 related martensitic grades) — CEN (2014)
  3. ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
  4. ASM Specialty Handbook — Stainless Steels — ASM International (1994)
  5. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.