S43932 is a dual-stabilized (niobium and titanium) ferritic stainless steel containing about 18% chromium and no deliberate nickel. This datasheet presents the material within the American (ASTM / ASME / UNS) standard system.
With nominally 18% chromium stabilized by both niobium and titanium, 441 provides good high-temperature strength — exceeding that of Types 409 and 439 — together with good oxidation and corrosion resistance in many exhaust-gas environments. The dual stabilization ties up carbon and nitrogen, preventing sensitisation and giving excellent weldability without post-weld annealing, while the niobium in solid solution improves elevated-temperature strength and creep resistance. Being ferritic and nickel-free, it is magnetic, cannot be hardened by heat treatment, is largely immune to chloride stress-corrosion cracking, and offers good formability for a ferritic grade.
Typical applications include hot-end automotive exhaust components (manifolds, flexible connectors, converters), heat-exchanger parts, and elevated-temperature equipment requiring strength and oxidation resistance at low cost.
Typical values, annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.7 | g/cm³ |
| Melting range | 1480–1530 | °C |
| Elastic modulus | 220 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.4 | µm/m·°C |
| Thermal conductivity (100 °C) | 25.0 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Ferritic | — |
Specified per ASTM A240 (UNS S43940 / S43932).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 17.5 | 18.5 | Corrosion / oxidation resistance |
| Niobium | Nb | 0.30 | 1.00 | Primary stabiliser; high-temperature strength |
| Titanium | Ti | 0.10 | 0.60 | Co-stabiliser; ties up C and N |
| Nickel | Ni | — | 0.50 | Residual |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser |
| Carbon | C | — | 0.030 | Low (stabilised, weldability) |
| Nitrogen | N | — | 0.030 | Low (stabilised) |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.030 | Residual impurity |
Nominal: 18Cr dual-stabilized (Nb + Ti) ferritic stainless steel; Nb + Ti ≥ 0.20 + 4×(C+N).
Annealed condition, per ASTM A240 for UNS S43940 / S43932.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (UTS) | ≥430 MPa |
| Annealed | 0.2% yield strength | ≥205 MPa |
| Annealed | Elongation at break | ≥18 % |
| Annealed | Hardness | ≤217 HB (~95 HRB) |
| — | Elastic modulus | 220 GPa |
Confirm against the mill test report. High-temperature strength exceeds Types 409 and 439 owing to solid-solution niobium.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Very Good | Comparable to 304 in many media |
| Exhaust-gas / condensate | Very Good | Designed for hot-end exhaust |
| Chloride stress-corrosion cracking | Very Good | Ferritic — largely immune |
| Pitting / crevice corrosion | Moderate | Below molybdenum-bearing grades |
| Oxidation (elevated temperature) | Very Good | Superior to 409 / 439; useful to ~950 °C |
Corrosion resistance is comparable to 304 in many environments, with the advantage of immunity to chloride stress-corrosion cracking and superior high-temperature strength among the standard ferritics.
A ferritic grade; cannot be hardened by heat treatment. Properties are set by annealing.
Anneal Heat to approximately 815–950 °C and air cool. Owing to dual stabilization, post-weld annealing is not required to restore intergranular corrosion resistance. Avoid prolonged exposure near 475 °C (embrittlement).
Excellent weldability without sensitisation owing to dual (Nb + Ti) stabilization; post-weld annealing is not required. The weld retains base-metal corrosion resistance and most mechanical properties.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Very Good | AWS A5.9 ER439 / stabilized ferritic, or Ni-base |
| GMAW / MIG | Good | Stabilized ferritic filler |
| Resistance / seam | Very Good | — |
Use a stabilized stainless or nickel-base filler to maintain weld-metal corrosion resistance. No post-weld anneal required.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Good; similar to other ferritic grades |
| Work hardening | Low rate — good formability |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Good — bending, roll forming, deep drawing |
| Hot forming | ~1100–800 °C; anneal afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Automotive | Exhaust manifolds, flexible connectors, converters | High-temperature strength + oxidation resistance |
| Heat transfer | Heat-exchanger components | Thermal stability + corrosion resistance |
| Elevated temperature | Furnace and burner parts | Oxidation resistance + creep strength |
| General industrial | Welded and formed components | SCC resistance + weldability |
| Product Form | ASTM Standard | ASME Code |
|---|---|---|
| Plate, sheet and strip | ASTM A240 | ASME SA-240 |
| Seamless / welded tube | ASTM A268 | ASME SA-268 |
| Bar and shapes | ASTM A479 | — |
| Welding consumables | AWS A5.9 ER439 | — |
Dual-stabilized (Nb + Ti) ferritic stainless steel. UNS S43940 / S43932.
| UNS | Cr % | Stabiliser | C % | Best Used For |
|---|---|---|---|---|
| S43932 | 17.5–18.5 | Nb + Ti | ≤0.03 | 18Cr dual-stabilized ferritic; hot exhaust, high-T strength |
| S43035 | 17–19 | Ti | ≤0.07 | 18Cr-Ti ferritic; cold-end exhaust |
| S40920 | 10.5–11.7 | Ti | ≤0.03 | 11Cr muffler-grade ferritic |
| S43000 | 16–18 | — | ≤0.12 | General ferritic; non-stabilized |
| S44400 | 17.5–19.5 | Ti / Nb | ≤0.025 | 18Cr-2Mo ferritic; higher corrosion resistance |




