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
446 is a high-chromium ferritic heat-resistant stainless steel containing about 23–27% chromium. This datasheet presents the material within the American (ASTM / ASME / UNS) standard system.
With nominally 25% chromium and no deliberate nickel or molybdenum, 446 offers excellent resistance to oxidation, sulfidation and other forms of hot corrosion, and is most commonly used between about 815 and 1150 °C. It is the only common heat-resistant alloy that will tolerate molten copper and brass. Its elevated-temperature strength is low compared with austenitic heat-resistant grades. Being a high-chromium ferritic, it is magnetic, cannot be hardened by heat treatment, and is largely immune to chloride stress-corrosion cracking, but it embrittles severely on exposure in the 425–540 °C range (475 °C / "885 °F" embrittlement) and forms sigma phase on long exposure around 540–700 °C.
Typical applications include furnace parts, kiln and annealing-box components, burner and combustion hardware, glass moulds, and equipment handling molten copper or brass.
Typical values, annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.5 | g/cm³ |
| Melting range | 1425–1510 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.4 | µm/m·°C |
| Thermal conductivity (100 °C) | 20.9 | W/m·K |
| Specific heat (20 °C) | 500 | J/kg·K |
| Structure | Ferritic | — |
Specified per ASTM A240 (UNS S44600).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 23.0 | 27.0 | Oxidation / hot-corrosion resistance |
| Nickel | Ni | — | 0.50 | Residual |
| Manganese | Mn | — | 1.50 | Deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser; oxidation resistance |
| Nitrogen | N | — | 0.25 | Residual |
| Carbon | C | — | 0.20 | Strength |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.030 | Residual impurity |
Nominal: 25Cr high-chromium ferritic heat-resistant stainless steel.
Annealed condition, per ASTM A240 for UNS S44600.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (UTS) | ≥515 MPa |
| Annealed | 0.2% yield strength | ≥275 MPa |
| Annealed | Elongation at break | ≥20 % |
| Annealed | Hardness | ≤201 HB (~95 HRB) |
| — | Elastic modulus | 200 GPa |
Confirm against the mill test report. Elevated-temperature strength is low; the alloy is selected for oxidation/hot-corrosion resistance, not high-temperature strength.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Excellent | Best among the standard ferritics; to ~1150 °C |
| Sulfidation / hot corrosion | Excellent | High chromium resists sulphur-bearing atmospheres |
| Molten copper / brass | Unique | Only common heat-resistant alloy that tolerates it |
| Chloride stress-corrosion cracking | Very Good | Ferritic — largely immune |
| 425–540 °C exposure | Poor (embrittlement) | 475 °C embrittlement — avoid this range |
The high chromium content gives outstanding resistance to oxidation, sulfidation and hot corrosion; however, the alloy embrittles in the 425–540 °C range and forms sigma phase on long exposure around 540–700 °C.
A ferritic grade; cannot be hardened by heat treatment. Properties are set by annealing.
Anneal Heat to approximately 760–830 °C and air cool (rapid cooling through 540–425 °C is preferred to limit embrittlement). Do not use in the 425–540 °C range in service unless loss of room-temperature ductility is acceptable.
Weldable, but the weld and heat-affected zone suffer grain growth and embrittlement; use low heat input and an austenitic or nickel-base filler for ductility. Pre-heat (~150–230 °C) may help heavier sections.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Acceptable | Austenitic (309) or nickel-base for ductility |
| GMAW / MIG | Acceptable | Austenitic / nickel-base filler |
| SMAW / stick | Acceptable | 309-type electrode |
Weld metal and HAZ have reduced toughness; austenitic or nickel-base fillers are preferred.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Fair; high chromium increases tool wear |
| Work hardening | Low rate |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Limited — lower ductility than lower-Cr ferritics |
| Hot forming | ~1050–800 °C; anneal afterward; avoid slow cooling through embrittlement range |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Furnaces / heat treatment | Furnace parts, annealing boxes, muffles | Oxidation resistance to ~1150 °C |
| Combustion | Burner nozzles, combustion chambers | Hot-corrosion / sulfidation resistance |
| Glass / metals | Glass moulds, molten copper/brass handling | Unique molten-copper tolerance |
| Thermal processing | Kiln furniture, recuperators | High-temperature oxidation resistance |
| Product Form | ASTM Standard | ASME Code |
|---|---|---|
| Plate, sheet and strip | ASTM A240 | ASME SA-240 |
| Bar and shapes | ASTM A276 | ASME SA-276 |
| Welded tube | ASTM A268 | ASME SA-268 |
| Wire | ASTM A580 | — |
High-chromium ferritic heat-resistant stainless steel. UNS S44600.
| Grade | Cr % | Mo % | C % | Best Used For |
|---|---|---|---|---|
| 446 | 23–27 | — | ≤0.20 | High-Cr heat-resistant ferritic; oxidation to ~1150 °C |
| 430 | 16–18 | — | ≤0.12 | General ferritic; non-heat-resistant |
| 444 | 17.5–19.5 | 1.75–2.5 | ≤0.025 | 18Cr-2Mo ferritic; corrosion resistance |
| 310S | 24–26 | — | ≤0.08 | Austenitic heat-resistant (higher strength) |
| 309S | 22–24 | — | ≤0.08 | Austenitic heat-resistant |
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