Stainless Steel 409Cb-ANN (Annealed)
Heat-treated state · default condition
UNS S40940
Standard stocked condition for exhaust sheet, strip and welded tube — maximum ductility and formability.
Values for the ANN condition
Other 409Cb tempers and conditions
409Cb is listed in 3 conditions; see the grade overview at 409Cb.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefaultThis page Annealed | Standard stocked condition for exhaust sheet, strip and welded tube — maximum ductility and formability. | 255 | 430 | 32 | 150 HB | 2.9 % IACS |
Temper Rolled / skin-passed | Choose for clip, bracket and clamp strip where slightly higher yield and flatness beat maximum ductility. | 380 | 480 | 16 | 175 HB | 2.9 % IACS |
Cold Worked 1/4 Hard | Higher-strength strip or cold-drawn tube for stiffness-driven parts; forming must be limited. | 450 | 550 | 9 | 16 HRC | 2.9 % IACS |
What is 409Cb-ANN?
409Cb-ANN is 409Cb heat treated to ANN — standard stocked condition for exhaust sheet, strip and welded tube — maximum ductility and formability. 409Cb-ANN has a yield strength of 255 MPa (37 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi). 409Cb-ANN has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Advantages
- Low embodied carbon — 2.7 kg CO₂/kg, better than 99% of stainless steel grades
- Easy to machine — 55/100, better than 94% of stainless steel grades
- Conducts heat well — 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 87% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Readily welded — 85/100, better than 87% of stainless steel grades
Limitations
- Hard to polish — 50/100, worse than 93% of stainless steel grades
- Low strength — 255 MPa (37 ksi), worse than 87% of stainless steel grades
- Needs corrosion protection — 45/100, worse than 85% of stainless steel grades
409Cb-ANN properties
Typical room-temperature values for 409Cb-ANN; 21 are specific to this condition. Other listed values are 409Cb reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
409Cb-ANN has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical15
409Cb-ANN has a yield strength of 255 MPa (37 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
409Cb-ANN is rated for continuous service to 760°C (1,400 °F). It conducts heat at 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 87% of stainless steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
409Cb-ANN conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 85% of stainless steel grades.
Sustainability4
Producing a kilogram of 409Cb-ANN takes about 40 MJ of energy and emits 2.7 kg of CO₂ — less than 97% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
409Cb-ANN's machinability is good (55/100, better than 94% of stainless steel grades); weldability excellent (85/100); formability very good (72/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 409Cb-ANN
Is 409Cb easy to machine?
Machines like a soft low-carbon stainless — use sharp, positive-rake tools, rigid setups and generous coolant to avoid built-up edge and work-hardened skin; roughly 65 % of B1112 speed.
Can 409Cb be welded?
Excellent weldability by GTAW/GMAW/laser/HF resistance welding; Nb stabilization prevents weld-decay and keeps HAZ ductility, but keep heat input low to limit grain coarsening and use 409Cb/430Nb or 309L filler.
Can 409Cb be formed, bent or molded?
Good cold formability for stamping, roll forming and tube bending; watch for ridging/roping on deep draws and allow more springback than austenitic grades.
What surface finishes work on 409Cb?
Not anodizable; normally supplied as mill 2B/No.1 finish, and can be aluminized, painted with high-temperature coatings or lightly polished for non-decorative service.
409Cb 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 |
|---|---|---|
| CC+N ≤ 0.045 typical mill practice | ≤ 0.03 | 0.02 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 1 | 0.45 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.02 | 0 |
| Cr | 10.5 – 11.7 | 11.2 |
| Ni | ≤ 0.5 | 0.25 |
| N | ≤ 0.03 | 0.02 |
| NbNb ≥ 10×C (Cb stabilization); some mills use Nb ≥ 0.30 | 0.17 – 0.75 | 0.35 |
| Tiresidual only in the pure Nb-stabilized version | ≤ 0.15 | 0.02 |
| Fe | balance | — |
409Cb-ANN — frequently asked
What is 409Cb-ANN used for?
409Cb-ANN is typically used for exhaust manifolds, catalytic converter housings and underbody automotive parts. In short: nb-stabilized exhaust ferritic; weldable to 760 °C; nickel-free, low cost.
What is the yield strength of 409Cb-ANN?
409Cb-ANN has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 87% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 409Cb-ANN easy to machine?
Reasonably — machinability is rated good (55/100, better than 94% of stainless steel grades). Machines like a soft low-carbon stainless — use sharp, positive-rake tools, rigid setups and generous coolant to avoid built-up edge and work-hardened skin; roughly 65 % of B1112 speed.
Can 409Cb-ANN be welded?
Yes — weldability is rated excellent (85/100). Excellent weldability by GTAW/GMAW/laser/HF resistance welding; Nb stabilization prevents weld-decay and keeps HAZ ductility, but keep heat input low to limit grain coarsening and use 409Cb/430Nb or 309L filler.
What surface finishes work on 409Cb-ANN?
Not anodizable; normally supplied as mill 2B/No.1 finish, and can be aluminized, painted with high-temperature coatings or lightly polished for non-decorative service.
Can 409Cb-ANN be formed, bent or molded?
Good cold formability for stamping, roll forming and tube bending; watch for ridging/roping on deep draws and allow more springback than austenitic grades.
What is the maximum service temperature of 409Cb-ANN?
409Cb-ANN is rated for continuous use to about 760°C (1,400 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 409Cb-ANN and 409Cb-CW14?
ANN is the default condition — standard stocked condition for exhaust sheet, strip and welded tube — maximum ductility and formability. CW14: higher-strength strip or cold-drawn tube for stiffness-driven parts; forming must be limited. Yield strength is 255 MPa in ANN versus 450 MPa in CW14.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip (S40940) — ASTM International (2023)
- ASTM A268/A268M — Seamless and Welded Ferritic and Martensitic Stainless Steel Tubing — ASTM International (2022)
- SAE J405 / ASTM A959 — Stainless steel designations (UNS S40940) — SAE / ASTM (2020)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- 409Cb / 11 Cr Nb-stabilized ferritic stainless product data — AK Steel / Cleveland-Cliffs, Outokumpu (2021)
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.