Stainless Steel 1.4446-AC (Spheroidize annealed)
Heat-treated state
EN 1.4446 · ASTM A351 CF3MN
Non-standard for pressure service; only for non-corrosive, non-code parts since Cr-rich phases and residual stresses remain.
Values for the AC condition
Other 1.4446 tempers and conditions
1.4446 is listed in 4 conditions; see the grade overview at 1.4446.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed 1050–1150 °C, water quenched | Standard delivery condition required by EN 10213 / ASTM A351 — maximum corrosion resistance and toughness. | 300 | 560 | 45 | 170 HB | — |
Hot isostatically pressed, then solution annealed and quenched | Pick when internal shrinkage porosity must be closed for pressure-boundary, cryogenic or fatigue-critical castings. | 310 | 580 | 52 | 175 HB | 2 % IACS |
ACThis page Spheroidize annealed | Non-standard for pressure service; only for non-corrosive, non-code parts since Cr-rich phases and residual stresses remain. | 310 | 540 | 30 | 185 HB | 2 % IACS |
Centrifugally cast tube/ring, solution annealed | Use for pipe, sleeves and rings where the denser, finer centrifugal structure gives slightly higher strength than static castings. | 320 | 590 | 42 | 180 HB | 2 % IACS |
What is 1.4446-AC?
1.4446-AC is 1.4446 heat treated to AC — non-standard for pressure service; only for non-corrosive, non-code parts since Cr-rich phases and residual stresses remain. 1.4446-AC has a yield strength of 310 MPa (45 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 195 GPa (28.3 Msi). 1.4446-AC has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,390°C (2,534 °F). SA is the default condition FabDigit quotes; AC is available on request or by drawing note.
Limitations
- High embodied carbon — 6.4 kg CO₂/kg, worse than 91% of stainless steel grades
- Limited formability — 22/100, worse than 82% of stainless steel grades
- Low electrical conductivity — 2 % IACS, worse than 77% of stainless steel grades
1.4446-AC properties
Typical room-temperature values for 1.4446-AC; 22 are specific to this condition. Other listed values are 1.4446 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4446-AC has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,390°C (2,534 °F).
Mechanical16
1.4446-AC has a yield strength of 310 MPa (45 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
1.4446-AC is rated for continuous service to 425°C (797 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 80% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
1.4446-AC conducts electricity at 2 % IACS, worse 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 1.4446-AC takes about 57 MJ of energy and emits 6.4 kg of CO₂ — more than 62% of stainless steel grades. Typical recycled content is 70%.
Manufacturability7
1.4446-AC's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability very good (72/100); formability poor (22/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4446-AC
Is 1.4446 easy to machine?
Machine like 316L but with more rigidity: sharp positive-rake carbide, heavy positive feed to cut under the work-hardened skin, 60–100 m/min with flood emulsion.
Can 1.4446 be welded?
Excellent with GTAW/SMAW using 316L or 309MoL fillers; no post-weld heat treatment needed for corrosion, keep interpass below ~150 °C and heat input low to limit ferrite/σ.
Can 1.4446 be formed, bent or molded?
Produced by sand, investment or centrifugal casting; long freezing range needs generous risering and chills, followed by mandatory 1050–1150 °C solution + water quench.
What surface finishes work on 1.4446?
Pickle and passivate (HNO3/HF) after casting and welding to restore the passive film; can be shot-blasted, electropolished or mechanically polished, no anodizing.
1.4446 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 |
|---|---|---|
| Clow-carbon for intergranular corrosion resistance | ≤ 0.03 | 0.02 |
| Si | ≤ 1 | 0.6 |
| Mn | ≤ 2 | 1.2 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.03 | 0.01 |
| Cr | 16.5 – 18.5 | 17.5 |
| Ni | 12 – 14 | 13 |
| MoASTM CF3MN counterpart is leaner (2.0–3.0 % Mo) | 3.5 – 4.5 | 4 |
| Nsolid-solution strengthening + pitting resistance | 0.12 – 0.22 | 0.17 |
| Fe | balance | — |
1.4446-AC — frequently asked
What is 1.4446-AC used for?
1.4446-AC is typically used for high-strength valve bodies, offshore pump casings and cryogenic components. In short: strongest low-carbon cast 316 type; nitrogen-strengthened CF3MN.
What is the yield strength of 1.4446-AC?
1.4446-AC has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 63% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.4446-AC easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Machine like 316L but with more rigidity: sharp positive-rake carbide, heavy positive feed to cut under the work-hardened skin, 60–100 m/min with flood emulsion.
Can 1.4446-AC be welded?
Yes — weldability is rated very good (72/100). Excellent with GTAW/SMAW using 316L or 309MoL fillers; no post-weld heat treatment needed for corrosion, keep interpass below ~150 °C and heat input low to limit ferrite/σ.
What surface finishes work on 1.4446-AC?
Pickle and passivate (HNO3/HF) after casting and welding to restore the passive film; can be shot-blasted, electropolished or mechanically polished, no anodizing.
Can 1.4446-AC be formed, bent or molded?
Produced by sand, investment or centrifugal casting; long freezing range needs generous risering and chills, followed by mandatory 1050–1150 °C solution + water quench.
What is the maximum service temperature of 1.4446-AC?
1.4446-AC is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4446-SA and 1.4446 CENT-SA?
SA is the default condition — standard delivery condition required by EN 10213 / ASTM A351 — maximum corrosion resistance and toughness. CENT-SA: use for pipe, sleeves and rings where the denser, finer centrifugal structure gives slightly higher strength than static castings. Yield strength is 300 MPa in SA versus 320 MPa in CENT-SA.
Sources
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM (2020)
- ASTM A451/A451M — Centrifugally Cast Austenitic Steel Pipe — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (cast stainless) — ASM International (1990)
- Steel Castings Handbook — Steel Founders' Society of America (1995)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.