AISI 446 Stainless Steel Plate | A240 Type 446 | UNS S44600
What is AISI 446 Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 446 Stainless Steel Plate.
AISI 446 is widely known and searched under many different names and designations, including AISI 446, ASTM A240 Type 446, ASME SA240 Type 446, UNS S44600, 446 stainless steel, 446 stainless steel plate, SUS446, 1.4749, X18CrN28 and high-chromium ferritic 446. All these names refer to the same 23–27% chromium heat-resisting ferritic stainless steel.
AISI 446 has the highest chromium content among the common 400-series ferritic plate grades. The extra chromium forms a very stable oxide scale, giving excellent resistance to oxidation, sulfidation and scaling in furnace atmospheres. The grade remains magnetic, non-hardenable by conventional quench and temper, and is normally supplied annealed.
Typical uses include furnace parts, kiln liners, annealing boxes, heat-treatment fixtures, burner parts and other fabrications exposed to oxidizing or sulfur-bearing gases at elevated temperature. AISI 446 is not intended as a wet-chloride substitute for a240 316l.
SHH STEEL supplies AISI 446 as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery.
AISI 446 is frequently compared with A240 430, A240 439, A240 441, A240 444, a240 309s and a240 310s. SHH STEEL provides technical support to help customers choose the most appropriate heat-resisting grade.
Material Specification
| pecification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 446 / A240 Type 446 / UNS S44600 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, EN 1.4749 related | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Annealed | Standard |
| Thickness Range | 1 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000–12000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply dual-certified ASTM A240 / ASME SA240 Type 446 material when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 446 (UNS S44600):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.20 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.50 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 23.00 – 27.00 |
| Nickel (Ni) | ≤ 0.75 |
| Nitrogen (N) | ≤ 0.25 |
| Iron (Fe) | Balance |
The defining feature of AISI 446 is the 23–27% chromium range. This high chromium level provides outstanding oxidation and scaling resistance in air and many furnace gases. Nitrogen may be present to strengthen the ferritic matrix. SHH STEEL carefully controls chromium so high-temperature performance remains consistent.
Mechanical Properties
Annealed Condition (typical ASTM A240 values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2%) | ≥ 275 MPa (40 ksi) |
| Elongation (in 50 mm) | ≥ 20% |
| Hardness | ≤ 217 HBW |
AISI 446 is supplied annealed, with higher strength than standard 430 because of the high chromium and possible nitrogen content. It is magnetic and cannot be hardened by conventional quench and temper. SHH STEEL supplies AISI 446 meeting A240 mechanical limits.
Physical Properties
Density is approximately 7.55–7.65 g/cm³. Melting range is approximately 1425–1510°C. Useful continuous oxidation resistance in air is typically up to about 1090–1100°C, depending on atmosphere and thermal cycling.
Material Comparison
| Grade | UNS | Cr (%) | Structure | Oxidation Resistance | Typical Preference |
|---|---|---|---|---|---|
| AISI 430 | S43000 | 16–18 | Ferritic | Good | Appliances and indoor service |
| AISI 439 | S43035 | 17–19 | Ferritic | Better welded | Exhaust and welded ferritic service |
| AISI 442 | S44200 | 18–23 | Ferritic | Better high-temp | Moderate furnace oxidation |
| AISI 446 | S44600 | 23–27 | Ferritic | Excellent | Severe furnace oxidation / scaling |
| AISI 309S | S30908 | 22–24 | Austenitic | Excellent | High-temp oxidizing service |
| AISI 310S | S31008 | 24–26 | Austenitic | Outstanding | Most severe high-temp oxidation |
AISI 446 is selected when a ferritic, low-nickel plate must resist severe oxidation. Compared with A240 430 or A240 439, chromium is much higher. For the most demanding cyclic oxidation or carburizing service, SHH STEEL also compares a240 309s and a240 310s.
Corrosion Resistance
AISI 446 offers outstanding resistance to high-temperature oxidation and good resistance to sulfidizing furnace gases because of its 23–27% chromium. At room temperature it also resists many oxidizing acids better than lower-chromium ferritics.
It is not a wet-chloride grade. In seawater, process chlorides or reducing acids, pitting or rust staining can occur. For those environments SHH STEEL recommends a240 316l or A240 444.
Weldability
AISI 446 can be welded by standard fusion methods, but heat input must be tightly controlled. High chromium and relatively high carbon increase the risk of grain growth and reduced toughness in the heat-affected zone.
Matching high-chromium ferritic or appropriate heat-resisting fillers are selected according to the design. Preheat and post-weld annealing may be required on thicker sections. For easier welded ferritic fabrications, SHH STEEL often recommends titanium-stabilized A240 439. Proper welding procedures and post-weld cleaning are required.
Heat Treatment
AISI 446 is normally supplied in the annealed condition by SHH STEEL.
Annealing restores ductility after hot working and prepares the plate for fabrication. The grade cannot be hardened by conventional quench and temper. SHH STEEL controls heat treatment so AISI 446 remains suitable for high-temperature oxidizing service.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 446 No.1 / A240 446 No.1 – industrial furnace plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 446 2B – thinner plate and sheet |
| Special | Ground or custom finishes | AISI 446 Special – on request |
SHH STEEL regularly supplies AISI 446 in No.1 finish for furnace and industrial plate applications.
Tolerances
Dimensional tolerances for AISI 446 Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 1 mm – 50 mm, width up to 1500–2000 mm, and length up to 6000–12000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| AISI 446 | AISI | Main commercial keyword |
| A240 Type 446 | ASTM A240 / ASME SA240 | Plate specification |
| UNS S44600 | Unified Numbering System | Primary UNS designation |
| 1.4749 / X18CrN28 | EN (Europe) | Closest European heat-resisting ferritic |
| SUS446 | JIS (Japan) | Japanese related grade |
| Related 16Cr25N / high-Cr | GB/T (China) | Chinese related grades |
| Related 430 / 439 / 310S | Multiple | Lower-Cr ferritic / austenitic options |
Related grades for comparison include A240 430, A240 439, A240 441, A240 444, a240 309s and a240 310s.
Applications
AISI 446 is selected for severe high-temperature oxidizing service where a ferritic, low-nickel plate is preferred. Typical applications of AISI 446 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Furnace & Heat Treatment | AISI 446 furnace parts, fixtures, trays and annealing boxes |
| Kilns & Industrial Heating | AISI 446 kiln liners, burner parts and oxidizing-atmosphere fabrications |
| Power & Energy | AISI 446 high-temperature ducts and covers |
| Petrochemical | AISI 446 heat-resistant process fabrications |
| Sulfur-Bearing Furnace Gases | AISI 446 components needing scaling and sulfidation resistance |
| Equipment Manufacturing | A240 Type 446 No.1 plate for high-temperature constructions |
SHH STEEL supplies AISI 446 for these high-temperature applications with consistent quality. For related industry solutions, see our energy industry, petrochemical industry and equipment manufacturing pages. Supporting services include steel cutting services and steel welding services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and sheet. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 446 with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- High-chromium AISI 446 material optimized for severe furnace oxidation
- Flexible dimensions and surface finishes (including AISI 446 No.1 and AISI 446 2B)
- Technical support for selection among AISI 430, 439, 446, 309S and 310S
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What are the other common names for AISI 446?AISI 446 is also known as ASTM A240 Type 446, UNS S44600, SUS446, 1.4749 and X18CrN28. SHH STEEL can certify the required designation.
- What is the difference between AISI 446 and AISI 430?AISI 446 has 23–27% chromium versus 16–18% in 430, so oxidation and scaling resistance at high temperature are much better. SHH STEEL recommends 446 for furnace service and 430 for appliances.
- What is the difference between AISI 446 and AISI 310S?446 is a ferritic, low-nickel grade. 310S is an austenitic 25Cr-20Ni grade with better toughness and often better cyclic oxidation performance. SHH STEEL can help select based on temperature, atmosphere and fabrication method.
- Is AISI 446 magnetic?Yes. AISI 446 is ferritic and remains magnetic in the annealed condition.
- hat is the density of AISI 446?Approximately 7.55–7.65 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- What is the maximum service temperature of AISI 446?Continuous oxidation resistance in air is typically up to about 1090–1100°C, depending on atmosphere and cycling. SHH STEEL can review the actual operating conditions.
- Does SHH STEEL supply dual-certified ASTM A240 Type 446 / AISI 446 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 446 Stainless Steel Plate is a 23–27% chromium ferritic grade designed for severe high-temperature oxidation and scaling resistance. It is the practical low-nickel choice for furnace parts, kiln liners, annealing boxes and other fabrications exposed to oxidizing or sulfur-bearing furnace gases.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 446 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 446 No.1 and AISI 446 2B), or a competitive quotation.
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