Stainless Steel S40945
UNS S40945
S40945 is a 409-family ferritic stainless with elevated titanium stabilization, aimed at retaining corrosion resistance in the heat-affected zone after welding.
Reference datasheet — S40945 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed condition
S40945 tempers and conditions
S40945 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault cold rolled, annealed and pickled (2B / 2D sheet & strip) | Standard stocked condition for exhaust sheet and tube stock — best formability and weldability. | 250 | 450 | 32 | 145 HB | — |
As-welded deposit | Typical condition of ERW/laser-welded exhaust tubing — Ti stabilization keeps the HAZ corrosion-resistant without annealing. | 255 | 440 | 25 | 155 HB | 2.9 % IACS |
Temper rolled / skin passed after anneal | Light cold roll for flatness, stretcher-strain suppression and a modest strength bump in roll-formed parts. | 330 | 480 | 25 | 165 HB | 2.9 % IACS |
Quarter hard | Occasional cold-worked strip order when higher yield is needed for clamps, brackets and stiff roll-formed sections. | 450 | 550 | 12 | 13 HRC | 2.9 % IACS |
Supply forms, finishes and certifications
Ways S40945 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
BA | Bright annealed | Surface finish |
HRAP | Hot rolled, annealed and pickled plate | Surface finish |
What is S40945?
S40945 is a 409-family ferritic stainless with elevated titanium stabilization, aimed at retaining corrosion resistance in the heat-affected zone after welding. It is used for welded exhaust assemblies in sheet, strip and welded tube, available annealed, HRAP, BA, temper-rolled, 1/4H and as-welded, with 250 MPa yield, 450 MPa tensile, 32 % elongation and 145 HB (78 HRB). Maximum service temperature is about 675 °C, corrosion resistance is limited to mildly aggressive environments, and the grade cannot be anodized. Choose S40975 or a 439/441 grade when deeper draws or higher oxidation resistance are required. S40945 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F). S40945 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi).
What is S40945 used for?
- welded exhaust assemblies
- mufflers
- tail pipes
Advantages
- Low embodied carbon — 2.6 kg CO₂/kg, better than 100% of stainless steel grades
- Easy to machine — 60/100, better than 98% of stainless steel grades
- Conducts heat well — 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades
- Readily welded — 88/100, better than 91% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
Limitations
- Needs corrosion protection — 38/100, worse than 95% of stainless steel grades
- Low strength — 250 MPa (36.3 ksi), worse than 91% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
S40945 properties
Typical room-temperature values for S40945-Annealed; bars are the position among stainless steel grades.
Physical3
S40945 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical15
S40945 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
S40945 is rated for continuous service to 675°C (1,247 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades. Thermal expansion is 11.4 µm/m·K (6.33 µin/in·°F).
Electrical3
S40945 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 95% of stainless steel grades.
Sustainability4
Producing a kilogram of S40945 takes about 36 MJ of energy and emits 2.6 kg of CO₂ — less than 99% of stainless steel grades. Typical recycled content is 70%.
Manufacturability7
S40945's machinability is good (60/100, better than 98% of stainless steel grades); weldability excellent (88/100); formability very good (72/100).
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. S40945 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S40945
Is S40945 easy to machine?
Machines much like a low-carbon steel — cuts more freely than 304, but keep tools sharp, use positive rake and rigid setups to avoid the smearing/BUE typical of ferritics.
Can S40945 be welded?
Excellent — GTAW/GMAW/laser/resistance welding without preheat or post-weld anneal; Ti stabilization prevents HAZ sensitization, use 409Ti/430Ti or 309L filler and keep heat input low to limit grain coarsening.
Can S40945 be formed, bent or molded?
Good deep drawing and roll forming (high r, low n); allow generous bend radii (≥1t) and expect less stretch-formability and more springback than austenitic 304; keep forming above ~10 °C to stay clear of the ductile-brittle transition.
S40945 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 stabilization efficiency | ≤ 0.03 | 0.02 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.02 | 0 |
| Cr | 10.5 – 11.7 | 11.2 |
| Ni | ≤ 0.5 | 0.2 |
| TiTi ≥ 8×(C+N) — the high-Ti stabilization that defines S40945 | 0.15 – 0.5 | 0.25 |
| N | ≤ 0.03 | 0.02 |
| Fe | balance |
What surface finishes work on S40945?
Cannot be anodized — passivate or paint; commonly used bare in exhaust duty where a light surface rust film is acceptable, or aluminized/ceramic-coated for cosmetic and long-life applications.
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).
Passivation
Organic Coating
Thermal Spray
How much does S40945 cost?
S40945 is a standard-cost stainless steel ($$), cheaper than about 71% 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.
S40945 — frequently asked
What is S40945 used for?
S40945 is typically used for welded exhaust assemblies, mufflers and tail pipes. In short: highly stabilized 409 variant; best HAZ corrosion resistance; weldable without preheat.
What is the yield strength of S40945?
S40945 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 91% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is S40945 easy to machine?
Reasonably — machinability is rated good (60/100, better than 98% of stainless steel grades). Machines much like a low-carbon steel — cuts more freely than 304, but keep tools sharp, use positive rake and rigid setups to avoid the smearing/BUE typical of ferritics.
Can S40945 be welded?
Yes — weldability is rated excellent (88/100). Excellent — GTAW/GMAW/laser/resistance welding without preheat or post-weld anneal; Ti stabilization prevents HAZ sensitization, use 409Ti/430Ti or 309L filler and keep heat input low to limit grain coarsening.
What surface finishes work on S40945?
Cannot be anodized — passivate or paint; commonly used bare in exhaust duty where a light surface rust film is acceptable, or aluminized/ceramic-coated for cosmetic and long-life applications.
Can S40945 be formed, bent or molded?
Good deep drawing and roll forming (high r, low n); allow generous bend radii (≥1t) and expect less stretch-formability and more springback than austenitic 304; keep forming above ~10 °C to stay clear of the ductile-brittle transition.
What is the maximum service temperature of S40945?
S40945 is rated for continuous use to about 675°C (1,247 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S40945 Annealed and S40945-TR?
Annealed is the default condition — standard stocked condition for exhaust sheet and tube stock — best formability and weldability. TR: light cold roll for flatness, stretcher-strain suppression and a modest strength bump in roll-formed parts. Yield strength is 250 MPa in Annealed versus 330 MPa in TR.
How much does S40945 cost?
S40945 is a standard-cost stainless steel ($$), cheaper than about 71% 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.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM A268/A268M — Seamless and Welded Ferritic Stainless Steel Tubing — ASTM International (2022)
- SAE J405 — Chemical Compositions of SAE Wrought Stainless Steels — SAE International (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- Type 409 / 409 Ti ferritic stainless steel product data — AK Steel / Cleveland-Cliffs (2020)
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.