SUS439 Stainless Steel Plate & Coil: Titanium-Stabilized Ferritic Industrial Plate/Coil

SUS439 is a titanium-stabilized ferritic stainless steel with about 18% chromium, supplied as plate, coil and strip. It is designated UNS S43932, EN 10088-2 1.4510 (X2CrTi18) and GB 022Cr18Ti. The addition of titanium makes the grade resistant to intergranular corrosion after welding, which is the weakness of unstabilized ferritic grades such as SUS430. For medium-temperature industrial components, SUS439 offers many of the benefits of austenitic grades at lower alloy cost.

Chemical Composition

Composition limits below follow JIS G4304 (SUS439) and EN 10088-2 (1.4510).

Element (wt%)	SUS439 / 1.4510
C	≤0.030
Si	≤1.00
Mn	≤1.00
P	≤0.040
S	≤0.030
Cr	17.00-19.00
Ti	EN 1.4510: 4(C+N)+0.15 min to 0.80 max; JIS SUS439 is titanium-stabilized with a comparable minimum tied to carbon and nitrogen content

Mechanical and Physical Properties

Annealed plate and coil per JIS G4304: tensile strength ≥450 MPa, yield strength ≥205 MPa, elongation ≥22%, hardness ≤183 HB. Physical data (typical): density 7.70 g/cm3, melting range approximately 1425-1510 C.

What Titanium Stabilization Gives You

Intergranular corrosion resistance after welding

In unstabilized ferritic stainless steel, welding can precipitate chromium carbides at grain boundaries, leaving the adjacent metal chromium-depleted and vulnerable to intergranular attack. Titanium in SUS439 preferentially forms titanium carbides, keeping chromium in solid solution and preserving corrosion resistance in the heat-affected zone.

Medium-temperature oxidation resistance

The 18% chromium content gives good oxidation resistance in air, and published engineering data rate SUS439 for continuous service up to about 800 C, which covers exhaust and heat-exchanger duty.

SUS439 vs SUS430

Property	SUS439	SUS430
Stabilizer	Titanium	None
Post-weld corrosion resistance	Excellent	Limited
High-temperature resistance	Better	Moderate
Typical applications	Industrial heat-resistant parts, exhaust systems, heat exchangers	Household, decorative and kitchenware

Applications

Heat-exchanger plates and tubes, automotive exhaust manifolds and catalytic-converter shells, water-heater tanks, oven liners, washing-machine drums and industrial ducting where both formability and weldability are required.

Fabrication and Welding

The ferritic structure gives excellent deep-drawing and bending behaviour, and SUS439 work-hardens slowly compared with austenitic grades. Welding is performed with low heat input to limit grain growth in the heat-affected zone; austenitic filler of the AWS ER308L type or a stabilized ferritic filler is commonly used, and post-weld annealing is generally not required thanks to titanium stabilization.

FAQ

1. What does titanium stabilization do in SUS439?

It binds carbon as titanium carbide, preventing chromium-carbide precipitation at grain boundaries during welding, and thereby preventing intergranular corrosion in the heat-affected zone.

2. How does SUS439 differ from SUS430?

SUS439 adds titanium stabilization and tighter carbon control, giving much better post-weld corrosion resistance and better high-temperature performance; SUS430 is cheaper but limited to mild, non-welded service.

3. Can SUS439 replace 304?

Where corrosion demands are moderate and service temperatures are medium, SUS439 is a cost-effective alternative. It is not a substitute where chloride pitting resistance or very low temperatures require austenitic grades.

4. What is the practical service-temperature limit?

Published engineering data rate SUS439 for continuous service up to about 800 C in oxidizing atmospheres, suitable for exhaust and heat-exchanger components.

5. In what forms is SUS439 supplied?

Plate, coil and strip in the annealed condition, with pickled, 2B or polished surfaces, and slit strip for tube and roll-forming applications.