446 Stainless Steel
446 is a high-chromium ferritic stainless steel selected for severe heat service. It is used when oxidation, scaling, and hot industrial atmospheres are the main risks. Many mills also add aluminum and silicon to strengthen the protective oxide film at high temperature.
As a ferritic stainless steel, 446 is magnetic in all conditions. It is typically chosen for furnaces, burners, heat shields, kiln parts, and other thermal equipment where common ferritic grades do not last long enough.
Chromium level
High (23–27% Cr)
Built for scaling and oxidation resistance in heat service.
Heat service
Up to ~1100°C
Typical continuous service guidance depends on atmosphere and design.
Atmosphere fit
Sulfur & hot gas
Used where sulfur-bearing and carburizing atmospheres are a concern.
Structure
Ferritic, magnetic
Stable at high temperature, with lower ductility than lower-Cr ferritic grades.
446 is mainly used for equipment that runs hot for long periods. It is also selected when the gas chemistry is aggressive and common stainless grades scale too fast.
- High-temperature systems: furnace tubes, heat shields, kiln components, burners, anchors, retorts
- Glass and ceramics: glass furnace parts, hot hardware near molten glass, ceramic kiln accessories
- Chemical and energy: petrochemical heaters, incinerator parts, catalyst supports
- Heat-treatment shops: baskets, fixtures, and high-temperature ducting
446 may be specified under different standard systems. Equivalents help alignment, but final acceptance should follow the purchase standard and test requirements.
| System | Designation | Note |
|---|---|---|
| AISI / ASTM | 446 | Common grade name (heat-resistant ferritic) |
| UNS | S44600 | Used in many material specifications |
| EN | 1.4762 | Common heat-resistant EN grade number |
| DIN / EN name | X10CrAlSi25 | Often shows Al/Si additions for scaling resistance |
| JIS | SUS446 | Common ordering name in Asia |
| GOST | 15Х28 | Seen in regional documents |
| GB | 00Cr26Al | China naming format for heat-resistant ferritic |
- High-temperature oxidation resistance: designed for scaling control in severe heat.
- Strong performance in hot industrial gases: often used in sulfur-bearing and carburizing atmospheres.
- Stable ferritic structure: magnetic, with reliable thermal stability.
- Cost control for heat service: chosen when nickel alloys are not required.
- Trade-off: lower ductility than lower-chromium ferritic grades, especially for cold forming.
Limits vary by standard and mill route. Use the Mill Test Certificate as the final verification for your delivered heat.
| Grade | Standard | C | Cr | Al / Si | Mn | Si | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|
| 446 / S44600 | ASTM A240 | ≤ 0.20 | 23.0–27.0 | Optional Al (by route) | ≤ 1.5 | ≤ 1.0 | ≤ 0.040 | ≤ 0.030 | Balance |
| 1.4762 | EN 10095 | ≤ 0.12 | 23.0–27.0 | 0.3–0.8 (Al/Si route) | ≤ 1.0 | 1.0–2.0 | ≤ 0.040 | ≤ 0.015 | Balance |
| 00Cr26Al | GB/T 20878 | ≤ 0.12 | 24.0–27.0 | Al addition | — | ≤ 1.0 | ≤ 0.040 | ≤ 0.030 | Balance |
Values depend on thickness, product form, and delivery condition. Use the governing specification for acceptance and design.
| Property | Typical reference | Notes |
|---|---|---|
| Tensile strength | 420–620 MPa | Confirm by thickness and condition |
| Yield strength | ≥ 275 MPa | Acceptance depends on standard and product form |
| Elongation | ≥ 20% | Lower ductility than lower-Cr ferritic grades |
| Hardness | ≤ 215 HBW | Reference for common supply routes |
446 is selected for hot environments where oxidation and scaling control are the main targets. In many industrial cases, it also performs well in sulfur-bearing gases, hot carburizing atmospheres, and molten salt exposure.
For heat exposure, many specifications and field references use a continuous-service guideline up to about 1100°C, supported by a stable oxide film and good thermal-cycle durability.
446 can be supplied in common stainless product forms. Availability depends on finish, tolerance, straightness, and inspection scope. Share your sizes and end use to align the best supply plan.
| Form | Typical size range | Notes |
|---|---|---|
| Sheet (cold rolled) | 0.3–6.0 mm, width 1000–2000 mm | Used for heat shields and thermal equipment parts |
| Plate (hot rolled) | 3–100 mm, width 1000–2000 mm | Common for furnace hardware and thick fabrication |
| Cold-rolled coil | 0.3–6.0 mm, width 1000–2000 mm | Slitting and cut-to-length available |
| Hot-rolled coil | 3–14 mm, width 1000–2000 mm | For heavier coil supply routes |
| Strip | 0.3–10 mm, width 7–600 mm | Often used for formed thermal components |
| Seamless pipe | OD ≤ 610 mm, WT 1–100 mm | Define NDT scope if needed |
| Welded pipe | OD 6–3000 mm, WT 1–100 mm | Confirm weld type and surface requirements |
| Round bar | Diameter 1–200 mm, length 100–12000 mm | Machined components and furnace parts |
| Flat bar | Width 20–800 mm, thickness 3–60 mm | Frames, supports, and high-heat fixtures |
| Angle bar | Side 20–250 mm, thickness 3–35 mm | Project-based supply by section size |
| Channel | Height 50–400 mm, thickness 4–20 mm | Project-based supply by section size |
| H beam | Height 100–1000 mm, thickness 6–40 mm | Project-based supply |
- Machining: use rigid setups and steady feeds. Slower speeds may help due to higher brittleness.
- Forming: ductility is lower than lower-Cr ferritic grades. Warm forming is often preferred for difficult shapes.
- Welding: preheating and controlled cooling reduce crack risk. Define filler selection based on service needs.
- Thermal equipment parts: common for heavy plates, rings, and furnace hardware.
446 is often supplied in hot-rolled and No.1 finishes for furnace and thermal equipment. Some cold-rolled supply is available, while special furnace-grade surface requirements can be arranged by project.
For heat service, chromium level and atmosphere resistance usually drive the choice. 446 is positioned for higher temperature and stronger sulfur resistance than common ferritic grades.
| Grade | Cr (typ.) | Max temp (guide) | Sulfur resistance | Chloride resistance | Cost |
|---|---|---|---|---|---|
| 430 | 16–18% | ~815°C | Low | Low | Low |
| 439 | 17–19% | ~850°C | Low | Medium | Low |
| 441 | 17.5–18.5% | ~900°C | Low | Medium | Low–medium |
| 444 | 17.5–19.5% | ~900°C | Medium | High | Medium |
| 446 | 23–27% | ~1100°C | Excellent | Good (not marine) | Medium–high |
Use these internal tools to confirm equivalents, check tolerances, and prepare a clear RFQ before purchasing.
How hot can 446 stainless steel run in continuous service?
Many applications use a continuous-service guideline up to about 1100°C. Final limits depend on the atmosphere, design, and thermal cycling profile.
Is 446 stainless steel magnetic?
Yes. 446 is a ferritic stainless steel and is magnetic in all conditions.
Can 446 be welded?
Yes, but it needs control. Preheating and slow cooling can reduce cracking risk. Share thickness and joint design so welding guidance can be matched to your job.
Is 446 similar to 316L?
Not in structure or chemistry. 316L is austenitic, while 446 is ferritic. For high-temperature oxidation and scaling, 446 is often selected as the stronger option.
What is 446 used for most often?
Furnaces, kilns, burners, heat shields, glass manufacturing equipment, incinerators, and other thermal processing systems.
Does 446 handle sulfur-bearing atmospheres?
Yes. 446 is commonly chosen for hot environments where sulfur-bearing gases are a major concern.
