Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
439 is a titanium-stabilized ferritic stainless steel containing about 18% chromium. This datasheet presents the material within the American (ASTM / ASME / UNS) standard system.
With nominally 18% chromium and a titanium stabilizing addition, 439 (also designated ASTM XM-8) resists corrosion in a wide range of oxidizing environments from fresh water to boiling acids. The titanium ties up carbon and nitrogen, so it can be welded without sensitisation and does not require post-weld annealing to restore ductility or intergranular corrosion resistance. It can be used in many oxidizing environments where Type 304 is adequate for general corrosion but is subject to chloride stress-corrosion cracking, and it is often substituted for Type 409 where higher thermal conductivity is needed. It offers superior formability and is widely used in automotive applications.
Typical applications include automotive exhaust systems (cold end), heat-exchanger and feedwater-heater tubing, hot-water tanks, and components requiring resistance to chloride stress-corrosion cracking.
Typical values, annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.7 | g/cm³ |
| Melting range | 1480–1530 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.4 | µm/m·°C |
| Thermal conductivity (100 °C) | 24.2 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Ferritic | — |
Specified per ASTM A240 (UNS S43035).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 17.0 | 19.0 | Corrosion / oxidation resistance |
| Titanium | Ti | 0.20 | 1.10 | Stabiliser; ties up C and N |
| Nickel | Ni | — | 0.50 | Residual |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser |
| Carbon | C | — | 0.070 | Low (stabilised, weldability) |
| Nitrogen | N | — | 0.040 | Low (stabilised) |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.030 | Residual impurity |
Nominal: 18Cr titanium-stabilized ferritic stainless steel.
Annealed condition, per ASTM A240 for UNS S43035.
| Condition | Property | Value |
|---|---|---|
| Annealed | Tensile strength (UTS) | ≥415 MPa |
| Annealed | 0.2% yield strength | ≥205 MPa |
| Annealed | Elongation at break | ≥22 % |
| Annealed | Hardness | ≤89 HRB |
| — | Elastic modulus | 200 GPa |
Confirm against the mill test report.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Very Good | Superior to 430; approaches 304 in many media |
| Oxidizing acids (e.g. nitric) | Good | Resists fresh water to boiling acids |
| Chloride stress-corrosion cracking | Very Good | Ferritic — largely immune (advantage over 304) |
| Pitting / crevice corrosion | Moderate | Below molybdenum-bearing grades |
| Oxidation (elevated temperature) | Good | Suited to exhaust cold-end service |
Corrosion resistance is well above 430 and, in many oxidizing media, approaches 304 — with the key advantage of immunity to chloride stress-corrosion cracking.
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 titanium stabilization, post-weld annealing is not required to restore intergranular corrosion resistance. Avoid prolonged exposure near 475 °C (embrittlement).
Readily welded without sensitisation owing to titanium stabilization; post-weld annealing is not required. The weld metal is free of the martensite normally associated with ferritic welds.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Very Good | AWS A5.9 ER439 (or stabilized / Ni-base for corrosion) |
| GMAW / MIG | Good | ER439 |
| Resistance / seam | 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 — superior formability |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Excellent — bending, flanging, deep drawing |
| Hot forming | ~1100–800 °C; anneal afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Automotive | Exhaust systems (cold end), trim | Oxidation resistance + formability |
| Heat transfer | Heat-exchanger and feedwater tubing | Thermal conductivity + SCC resistance |
| Water heating | Hot-water tanks, components | Corrosion resistance + weldability |
| General industrial | Formed and welded components | SCC resistance + formability |
| 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 | ASME SA-479 |
| Welded feedwater heater tubes | ASTM A803 | — |
| Welding consumables | AWS A5.9 ER439 | — |
Titanium-stabilized ferritic stainless steel. UNS S43035.
| Grade | Cr % | Stabiliser | C % | Best Used For |
|---|---|---|---|---|
| 439 | 17–19 | Ti | ≤0.07 | 18Cr-Ti ferritic; exhaust, SCC resistance, weldable |
| 409L | 10.5–11.7 | Ti | ≤0.03 | 11Cr muffler-grade ferritic |
| 430 | 16–18 | — | ≤0.12 | General ferritic; non-stabilized |
| 441 | 17.5–18.5 | Ti + Nb | ≤0.03 | 18Cr-Ti-Nb ferritic; hot exhaust |
| 444 | 17.5–19.5 | Ti / Nb | ≤0.025 | 18Cr-2Mo ferritic; higher corrosion resistance |
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