Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
440F is a free-machining, high-carbon, high-chromium martensitic stainless steel. This datasheet presents the material within the American (ASTM / SAE / UNS) standard system.
With about 17% chromium and roughly 1% carbon plus a sulphur addition, 440F is the free-machining version of 440C — it develops the same very high hardness on hardening and tempering while offering markedly improved machinability for high-volume production. The high carbon allows hardening to about 58–60 HRC for excellent wear resistance and edge retention, and the sulphur forms manganese-sulphide inclusions that break chips and improve tool life, at the cost of somewhat reduced corrosion resistance compared with 440C. It is martensitic, magnetic, and is supplied annealed for machining, then hardened and tempered to develop final properties.
Typical applications include cutlery and blade components, bearings, valve parts, nozzles, pump shafts, gauges and high-hardness wear components requiring extensive machining.
| Property | Value | Unit |
|---|---|---|
| Density | 7.7 | g/cm³ |
| Melting range | 1370–1480 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.2 | µm/m·°C |
| Thermal conductivity (100 °C) | 24.2 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Martensitic | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 16.0 | 18.0 | Corrosion resistance; carbide former |
| Carbon | C | 0.95 | 1.20 | High hardness (martensite + carbides) |
| Sulphur | S | 0.15 | — | Free-machining (MnS inclusions) |
| Molybdenum | Mo | — | 0.75 | Optional; hardenability |
| Manganese | Mn | — | 1.25 | Forms MnS; deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser |
| Phosphorus | P | — | 0.040 | Residual impurity |
Per ASTM A582 / A276 for UNS S44020.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (UTS) | ~760 MPa |
| Annealed | 0.2% yield strength | ~450 MPa |
| Annealed | Hardness | ≤269 HB (annealed) |
| Hardened & tempered | Hardness | ~58–60 HRC |
| Hardened & tempered | Tensile strength (UTS) | ~1900–2000 MPa |
Confirm against the mill test report. Maximum hardness and wear resistance are obtained after hardening and a low-temperature temper.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Moderate | Best in the hardened, polished, passivated condition |
| Fresh water / mild media | Moderate | Below 440C (sulphur reduces resistance) |
| Chloride pitting | Limited | Sulphide inclusions are initiation sites |
| Hardened vs annealed | Better hardened | Hardened + passivated gives best resistance |
| Seawater | Not recommended | — |
Corrosion resistance is moderate — somewhat below 440C owing to the sulphur — and is best in the hardened, tempered and passivated condition with a smooth surface.
A high-carbon martensitic grade; hardened by quenching and tempering.
Anneal Heat to approximately 840–900 °C and slow furnace cool to ~600 °C for the soft, machinable condition (~230–269 HB).
Harden and Temper Austenitise at approximately 1010–1065 °C, quench in oil or air (warm parts), then temper. A low-temperature temper (~150–200 °C) develops maximum hardness (~58–60 HRC) and wear resistance. Avoid tempering in the 425–565 °C range (reduced toughness and corrosion resistance).
Not recommended for welding — the high carbon and sulphur promote hard, crack-sensitive welds. Where joining is unavoidable, preheat, use an austenitic filler, and post-weld heat treat.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Not recommended | Austenitic (309) if unavoidable |
| GMAW / MIG | Not recommended | — |
| Brazing | Preferred join method | — |
The high carbon and free-machining sulphur make this grade unsuitable for structural welding.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Annealed (machine soft, then harden) |
| Machinability | Good for a hardenable 440-type — improved by sulphur |
| Tooling | Carbide tooling; rigid setup |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Limited — high carbon, low ductility |
| Hot forming | ~1065–815 °C; anneal afterward, then harden |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Cutlery / blades | Knife blades, cutting tools | High hardness + edge retention |
| Bearings | Balls, races, rollers | Hardness + wear resistance |
| Valves / pumps | Valve parts, nozzles, shafts | Hardness + machinability |
| Instruments | Gauges, wear components | Dimensional stability + hardness |
| Product Form | ASTM Standard | SAE / Other |
|---|---|---|
| Bar and wire | ASTM A582 | SAE J405 (51440F) |
| Rod, bar and shapes | ASTM A276 | — |
| Forging stock | ASTM A314 | — |
| — | — | — |
Free-machining high-carbon martensitic stainless steel. UNS S44020.
| Grade | Cr % | C % | S % | Best Used For |
|---|---|---|---|---|
| 440F | 16–18 | 0.95–1.20 | ≥0.15 | Free-machining high-hardness martensitic; cutlery, bearings |
| 440C | 16–18 | 0.95–1.20 | ≤0.03 | High-hardness martensitic; non-free-machining |
| 440A | 16–18 | 0.60–0.75 | ≤0.03 | Lower-carbon martensitic; moderate hardness |
| 416 | 12–14 | ≤0.15 | ≥0.15 | Free-machining 12Cr martensitic |
| 430F | 16–18 | ≤0.12 | ≥0.15 | Free-machining ferritic |
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