Stainless Steel 446
AISI/SAE 446 · UNS S44600 · EN 1.4762, 1.4749 · JIS SUS446, SUH446
446 (S44600, SUS446, SUH446, 1.4762) is a high-chromium 23–27% Cr ferritic stainless used where oxidation and sulfur attack at temperature govern, supplied annealed, hot rolled and cold drawn.
Values for the Annealed condition
446 tempers and conditions
446 is supplied in 3 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault mill annealed (sheet, plate, bar, tube) | Standard stocked condition for all heat-resisting fabrication; anneal 760–830 °C and cool rapidly through 550–400 °C to avoid embrittlement. | 350 | 550 | 22 | 180 HB | — |
as-rolled plate and bar | Pick for heavy plate and hot-finished bar where a mill anneal is not required before further hot working. | 380 | 570 | 20 | 190 HB | 2.6 % IACS |
cold-drawn/cold-finished bar and wire | Choose cold-drawn bar for tighter tolerance, better surface and higher strength where ductility and toughness are not critical. | 480 | 620 | 15 | 16 HRC | 2.6 % IACS |
What is 446?
446 (S44600, SUS446, SUH446, 1.4762) is a high-chromium 23–27% Cr ferritic stainless used where oxidation and sulfur attack at temperature govern, supplied annealed, hot rolled and cold drawn. It resists scaling to 1095 °C, the highest of the standard ferritics, with 350 MPa yield, 550 MPa tensile and 22% elongation. Cold formability is only fair (score 40) and machinability is about 50% of AISI 1212; the grade is subject to 475 °C embrittlement and HAZ grain coarsening, so welded joints lose toughness. Where load-bearing strength at temperature is needed, use an austenitic such as 309 or 310. 446 has a density of 7.5 g/cm³ (0.271 lb/in³), lighter than 99% of stainless steel grades. It melts at 1,425°C (2,597 °F). 446 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 52% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
What is 446 used for?
- Furnace parts and linings
- Exhaust and flue ducts
- Radiant tubes
- Burner nozzles and heads
- Heat treatment fixtures and baskets
- Sulfur-bearing flue gas ductwork
- Thermocouple protection tubes
Advantages
- High service temperature — 1,095°C (2,003 °F), better than 94% of stainless steel grades
- Easy to machine — 45/100, better than 84% of stainless steel grades
- High electrical conductivity — 2.6 % IACS, better than 77% of stainless steel grades
- Conducts heat well — 20.9 W/m·K (12.1 BTU/hr·ft·°F), better than 75% of stainless steel grades
Limitations
- Difficult to weld — 30/100, worse than 88% of stainless steel grades
- Limited ductility — 22%, worse than 75% of stainless steel grades
446 properties
Typical room-temperature values for 446-Annealed; bars are the position among stainless steel grades.
Physical3
446 has a density of 7.5 g/cm³ (0.271 lb/in³), lighter than 99% of stainless steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
446 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 52% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
446 is rated for continuous service to 1,095°C (2,003 °F). It conducts heat at 20.9 W/m·K (12.1 BTU/hr·ft·°F), better than 75% of stainless steel grades. Thermal expansion is 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
446 conducts electricity at 2.6 % IACS, better than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of 446 takes about 55 MJ of energy and emits 5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 50%.
Manufacturability7
446's machinability is fair (45/100, better than 84% of stainless steel grades); weldability poor (30/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 446 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 446
Is 446 easy to machine?
Machines like a soft ferritic stainless — rigid setup, sharp positive-rake carbide, heavy feed and flood coolant to break the gummy chip; rating ≈ 50 % of AISI 1212.
Can 446 be welded?
Weldable by GTAW/GMAW but HAZ grain coarsening embrittles the joint; use low heat input, no preheat above ~200 °C, 309/310 or matching high-Cr filler, and post-weld anneal at ~790 °C with fast cooling where possible.
Can 446 be formed, bent or molded?
Only fair cold formability — generous bend radii, forming above ~150–250 °C helps; hot work at 900–1150 °C and avoid slow cooling through 550–400 °C to prevent 475 °C embrittlement.
Manufacturability
The process limits FabDigit applies to 446. Every 446 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better45 / 100 |
|---|---|
| ISO material group | M.4 |
| Cutting speed (rough / finish) | 140 / 170 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better40 / 100 |
|---|---|
| Weldability | Fair30 / 100 |
| Bendable | Yes |
446 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.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CASTM A176/A240 Type 446 | ≤ 0.2 | 0.1 |
| Cr | 23 – 27 | 25 |
| Mn | ≤ 1.5 | |
| Si | ≤ 1 | |
| Niresidual limit in most product specs | ≤ 0.75 | |
| N | ≤ 0.25 | |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 446?
Pickle and passivate after hot work or welding; polishes to a bright ferritic finish, no anodising — service oxide scale is the intended protective layer.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 446 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 446 cost?
446 is a premium-cost stainless steel ($$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
446 — frequently asked
What is 446 used for?
446 is typically used for furnace parts and linings, exhaust and flue ducts, radiant tubes, burner nozzles and heads, heat treatment fixtures and baskets and sulfur-bearing flue gas ductwork. In short: heat-resistant ferritic stainless.
What is the yield strength of 446?
446 has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 52% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 446 easy to machine?
Reasonably — machinability is rated fair (45/100, better than 84% of stainless steel grades). Machines like a soft ferritic stainless — rigid setup, sharp positive-rake carbide, heavy feed and flood coolant to break the gummy chip; rating ≈ 50 % of AISI 1212.
Can 446 be welded?
Not readily — weldability is rated poor (30/100). Weldable by GTAW/GMAW but HAZ grain coarsening embrittles the joint; use low heat input, no preheat above ~200 °C, 309/310 or matching high-Cr filler, and post-weld anneal at ~790 °C with fast cooling where possible.
What surface finishes work on 446?
Pickle and passivate after hot work or welding; polishes to a bright ferritic finish, no anodising — service oxide scale is the intended protective layer.
Can 446 be formed, bent or molded?
Only fair cold formability — generous bend radii, forming above ~150–250 °C helps; hot work at 900–1150 °C and avoid slow cooling through 550–400 °C to prevent 475 °C embrittlement.
What is the maximum service temperature of 446?
446 is rated for continuous use to about 1,095°C (2,003 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 446 cost?
446 is a premium-cost stainless steel ($$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 446?
Yes — 446 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- ASTM A176 — Stainless and Heat-Resisting Chromium Steel Plate, Sheet, and Strip — ASTM International (2022)
- ASTM A276 — Stainless Steel Bars and Shapes — ASTM International (2023)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 1220 / GB/T 4237 (2Cr25N ) — SAC (2015)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.