Stainless Steel S43940
UNS S43940
S43940 (439 Type 3) is a Ti/Nb dual-stabilized 18 % Cr ferritic stainless close to Type 439, tuned to a specific stabilization window for exhaust and automotive trim sheet.
Reference datasheet — S43940 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 2B condition
S43940 tempers and conditions
S43940 is supplied in 3 conditions, soft to hard. Annealed 2B 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 |
|---|---|---|---|---|---|---|
2D | Choose the non-skin-passed dull matte cold-rolled and pickled finish for deep-drawn parts, where the rougher surface retains lubricant and formability edges above 2B. | 290 | 470 | 33 | 150 HB | 2.9 % IACS |
Annealed 2BDefault Cold rolled, annealed, pickled, skin passed | Pick this cold-rolled, annealed, pickled and skin-passed default for stamped and welded exhaust parts; 32 % elongation and a uniform surface suit forming and joining. | 300 | 480 | 32 | 155 HB | — |
Temper rolled / lightly cold worked strip (≈1/4 hard) | Use temper-rolled, lightly cold-worked strip (about 1/4 hard) for clamps, gaskets and formed coil needing 450 MPa yield and flatness; elongation drops to 14 %. | 450 | 550 | 14 | 195 HB | 2.9 % IACS |
Supply forms, finishes and certifications
Ways S43940 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Welded Tube Annealed | Welded tube | Supply form |
BA | Bright annealed | Surface finish |
HRAP No.1 | No.1 | Surface finish |
No.4 | Annealed, brushed/abrasive polished finish | Surface finish |
What is S43940?
S43940 (439 Type 3) is a Ti/Nb dual-stabilized 18 % Cr ferritic stainless close to Type 439, tuned to a specific stabilization window for exhaust and automotive trim sheet. Typical annealed properties are about 300 MPa yield, 480 MPa tensile, 32 % elongation and 155 HB, with service to 900 °C — higher than S43932 — and product forms from 2B and 2D annealed sheet through BA, No. 4, hot-rolled No. 1, temper-rolled strip and annealed welded tube. Dual stabilization keeps welds free of sensitization (weldability score 88) with good formability (78). Corrosion resistance (47) remains below austenitic 304 in chloride environments. S43940 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). S43940 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 210 GPa (30.5 Msi).
What is S43940 used for?
- exhaust hangers
- trim components
- heat shields
Advantages
- Low embodied carbon — 3.2 kg CO₂/kg, better than 95% 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
- Easy to machine — 50/100, better than 90% of stainless steel grades
- Forms and bends easily — 78/100, better than 90% of stainless steel grades
Limitations
- Needs corrosion protection — 47/100, worse than 81% of stainless steel grades
S43940 properties
Typical room-temperature values for S43940-Annealed 2B; bars are the position among stainless steel grades.
Physical3
S43940 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
S43940 has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
S43940 is rated for continuous service to 900°C (1,652 °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 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
S43940 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (47/100), worse than 81% of stainless steel grades.
Sustainability4
Producing a kilogram of S43940 takes about 48 MJ of energy and emits 3.2 kg of CO₂ — less than 85% of stainless steel grades. Typical recycled content is 70%.
Manufacturability7
S43940's machinability is fair (50/100, better than 90% of stainless steel grades); weldability excellent (88/100); formability very good (78/100).
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. S43940 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S43940
Is S43940 easy to machine?
Machinability is better than austenitic stainless, but Ti/Nb carbonitrides are abrasive to tooling: use coated carbide, moderate speeds with heavy feeds and generous coolant to prevent built-up edge and work hardening.
Can S43940 be welded?
Dual stabilization keeps the weld free of sensitization, so post-weld annealing is normally unnecessary. Use low heat input to limit heat-affected-zone grain growth; weld autogenously by TIG, MIG, laser or high-frequency, or use 309L or 430Nb-type filler.
Can S43940 be formed, bent or molded?
Good deep drawing, roll forming and hydroforming behaviour with r̄ of about 1.5–1.8. Springback is greater than low-carbon steel and must be compensated; avoid excessive through-thickness thinning and cold bending of heavy gauge to prevent brittle fracture.
S43940 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 A240 / EN 1.4509 maximum | ≤ 0.03 | 0.02 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.04 | 0.03 |
| SEN 1.4509 stricter: ≤0.015 | ≤ 0.03 | 0 |
| CrEN 1.4509: 17.5–18.5 | 17 – 19 | 18 |
| Niresidual element | ≤ 0.5 | 0.2 |
| N | ≤ 0.03 | 0.02 |
| TiEN 1.4509 range; ASTM A240 specifies only Ti+Nb | 0.1 – 0.6 | 0.2 |
| NbEN 1.4509: Nb ≥ 3×C + 0.30 ASTM A240: Ti+Nb = 0.20+4(C+N) min, 0.75 max | 0.3 – 1 | 0.45 |
| Fe | balance |
What surface finishes work on S43940?
Cannot be anodized. Common finishes are pickling and passivation, BA bright surface, No. 4 brushed, electropolishing and PVD colouring; remove weld heat tint to restore corrosion resistance.
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
Equivalent designations
Standards and trade names that resolve to Stainless Steel S43940 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 439 Type 3
How much does S43940 cost?
S43940 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.
S43940 — frequently asked
What is S43940 used for?
S43940 is typically used for exhaust hangers, trim components and heat shields. In short: 900 °C ferritic exhaust grade; sensitization-free welds; nickel-free 304 substitute.
What is the yield strength of S43940?
S43940 has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 68% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is S43940 easy to machine?
Reasonably — machinability is rated fair (50/100, better than 90% of stainless steel grades). Machinability is better than austenitic stainless, but Ti/Nb carbonitrides are abrasive to tooling: use coated carbide, moderate speeds with heavy feeds and generous coolant to prevent built-up edge and work hardening.
Can S43940 be welded?
Yes — weldability is rated excellent (88/100). Dual stabilization keeps the weld free of sensitization, so post-weld annealing is normally unnecessary. Use low heat input to limit heat-affected-zone grain growth; weld autogenously by TIG, MIG, laser or high-frequency, or use 309L or 430Nb-type filler.
What surface finishes work on S43940?
Cannot be anodized. Common finishes are pickling and passivation, BA bright surface, No. 4 brushed, electropolishing and PVD colouring; remove weld heat tint to restore corrosion resistance.
Can S43940 be formed, bent or molded?
Good deep drawing, roll forming and hydroforming behaviour with r̄ of about 1.5–1.8. Springback is greater than low-carbon steel and must be compensated; avoid excessive through-thickness thinning and cold bending of heavy gauge to prevent brittle fracture.
What is the maximum service temperature of S43940?
S43940 is rated for continuous use to about 900°C (1,652 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does S43940 cost?
S43940 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 (S43940) — ASTM International (2023)
- EN 10088-1 / 10088-2 — Stainless steels, X2CrTiNb18 (1.4509) — CEN (2014)
- 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)
- Ferritic stainless 1.4509 / 441 data sheet (exhaust-grade sheet & tube) — Outokumpu / Aperam (2022)
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.