Stainless Steel 1.4409-AT
Precip hard · default condition
EN 1.4409 · UNS J92800 · ASTM A351 CF3M
Standard delivery condition for all pressure-containing and corrosion-service castings; maximum corrosion resistance and ductility.
Values for the AT condition
Other 1.4409 tempers and conditions
1.4409 is listed in 4 conditions; see the grade overview at 1.4409.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Only for non-critical, non-corrosive structural castings; interdendritic segregation and residual stress remain, so corrosion service is not qualified. | 240 | 480 | 25 | 160 HB | 2.2 % IACS |
ATDefaultThis page solution annealed 1050–1150 °C and water quenched | Standard delivery condition for all pressure-containing and corrosion-service castings; maximum corrosion resistance and ductility. | 250 | 520 | 45 | 150 HB | — |
hot isostatically pressed then solution annealed | Choose for high-integrity valve/pump castings and NDT-critical parts where microporosity must be closed; slightly higher ductility and impact energy. | 260 | 530 | 50 | 152 HB | 2.3 % IACS |
Ferrite-balanced high-strength variant (ASTM A351), solution annealed | Use when higher allowable stress is needed from the same chemistry family; composition balanced for controlled δ-ferrite, but ASTM restricts service to ≤ 425 °C. | 275 | 570 | 40 | 160 HB | 2.3 % IACS |
What is 1.4409-AT?
1.4409-AT is 1.4409 in the AT condition — standard delivery condition for all pressure-containing and corrosion-service castings; maximum corrosion resistance and ductility. 1.4409-AT has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi). 1.4409-AT has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,390°C (2,534 °F).
Advantages
- Readily welded — 88/100, better than 91% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Low strength — 250 MPa (36.3 ksi), worse than 91% of stainless steel grades
- Limited formability — 20/100, worse than 86% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
1.4409-AT properties
Typical room-temperature values for 1.4409-AT; 12 are specific to this condition. Other listed values are 1.4409 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4409-AT has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,390°C (2,534 °F).
Mechanical15
1.4409-AT has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
1.4409-AT is rated for continuous service to 550°C (1,022 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 72% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
1.4409-AT conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), better than 73% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4409-AT takes about 52 MJ of energy and emits 4.5 kg of CO₂ — less than 76% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
1.4409-AT's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (88/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4409-AT
Is 1.4409 easy to machine?
Gummy and work-hardening: use rigid setups, sharp positive-rake carbide, 60–120 m/min with heavy feed, flood coolant, and avoid dwelling to prevent glazing.
Can 1.4409 be welded?
Excellent — GTAW/SMAW with 316L/E316L or ER316LMn filler, no preheat, keep interpass < 150 °C; repair welds on solution-annealed parts generally need no re-anneal thanks to the ≤0.03% C.
Can 1.4409 be formed, bent or molded?
Sand or investment cast at 1560–1600 °C with generous risering (≈2.3% solidification shrinkage); solution anneal 1050–1150 °C and water quench, then pickle/passivate.
What surface finishes work on 1.4409?
Shot blast, pickle in HNO3-HF then passivate per ASTM A967; electropolishing gives the best hygienic finish — no anodizing possible.
1.4409 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 | ≤ 1.5 | 1 |
| MnA351 CF3M allows ≤1.50 | ≤ 1.5 | 1 |
| PA351: ≤0.040 | ≤ 0.04 | 0.02 |
| SA351: ≤0.040 | ≤ 0.03 | 0.01 |
| CrA351 CF3M: 17.0–21.0 | 18 – 20 | 19 |
| NiA351 CF3M: 9.0–13.0 | 9 – 12 | 10.5 |
| MoA351 CF3M: 2.0–3.0 | 2 – 2.5 | 2.3 |
| N | ≤ 0.2 | 0.05 |
| Fe | balance | — |
1.4409-AT — frequently asked
What is 1.4409-AT used for?
1.4409-AT is typically used for welded chemical valve bodies, seawater pump casings and cryogenic fittings. In short: weld-repairable CF3M casting; low-carbon 316 equivalent.
What is the yield strength of 1.4409-AT?
1.4409-AT has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 91% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 1.4409-AT easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Gummy and work-hardening: use rigid setups, sharp positive-rake carbide, 60–120 m/min with heavy feed, flood coolant, and avoid dwelling to prevent glazing.
Can 1.4409-AT be welded?
Yes — weldability is rated excellent (88/100). Excellent — GTAW/SMAW with 316L/E316L or ER316LMn filler, no preheat, keep interpass < 150 °C; repair welds on solution-annealed parts generally need no re-anneal thanks to the ≤0.03% C.
What surface finishes work on 1.4409-AT?
Shot blast, pickle in HNO3-HF then passivate per ASTM A967; electropolishing gives the best hygienic finish — no anodizing possible.
Can 1.4409-AT be formed, bent or molded?
Sand or investment cast at 1560–1600 °C with generous risering (≈2.3% solidification shrinkage); solution anneal 1050–1150 °C and water quench, then pickle/passivate.
What is the maximum service temperature of 1.4409-AT?
1.4409-AT is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4409-AT and 1.4409 CF3MA?
AT is the default condition — standard delivery condition for all pressure-containing and corrosion-service castings; maximum corrosion resistance and ductility. CF3MA: use when higher allowable stress is needed from the same chemistry family; composition balanced for controlled δ-ferrite, but ASTM restricts service to ≤ 425 °C. Yield strength is 250 MPa in AT versus 275 MPa in CF3MA.
Sources
- EN 10283 — Corrosion resistant steel castings — CEN (2010)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM (2020)
- ASTM A743/A744 — Corrosion-Resistant Iron-Chromium-Nickel Castings — ASTM (2021)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- Steel Castings Handbook, 6th ed. — SFSA / ASM International (1995)
- Corrosion Handbook — Outokumpu (2015)
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.