439 Stainless Steel Alloy

UNS: S43900
EN-DIN: 1.4510

Printable PDF: 439 Stainless Steel Alloy Data Sheet

439 Oxidation resistance and corrosion resistance is superior to Type 409 in areas where temperatures may exceed the oxidation limit of Type 409 or where aqueous corrosion resistance, particularly to chlorides, is needed.  Applications include: Tubular manifolds and other exhaust system with difficult to form exhaust components.

Nominal Composition

C:	0.070 max
Mn:	1.0 max
P:	0.040 max
S:	0.030 max
Si:	1.00 max
Cr:	17.00 – 19.00
Ni:	0.50 max
Ti:	>=0.20+4(C+N) – 1.10
Al:	0.15
N:	0.040
Fe:	BAL

Physical Properties
At 70°F (At 20°C)      

Density
0.278 lb./in³ / (7685 kg/m³)

Modulus of Elasticity (E)
28.4 x 10³ ksi / (193 x 10³MPa)

Electrical Resistivity
24.0 μ ohm.in / (60.0 μ ohm.cm)

Applicable Specifications

ASTM A240

Typical Mechanical Properties – Typical Room Temperature Mechanical Properties

Typical mechanical properties are based on AK source, ASTM A240

Condition
Annealed

Tensile Strength (UTS)
66 ksi (455 MPa)

0.2% YS
43 ksi (296 MPa)

Elongation% in 2”  (50.8 mm)
32%

Hardness Rockwell
74 HRBW 

Additional Information on 439 Stainless Steel Alloy

Type 439 stainless steel is a Titanium-stabilized 17% to 18% Chromium ferritic stainless steel with improved weldability.  Due to its high Chromium content, corrosion resistance is much higher compared to type 409, in a variety of oxidizing environments, from fresh water to boiling acids.

Stainless steel 439 does not require annealing after welding to restore ductility or provide intergranular corrosion resistance. This type of steel is often used in applications that require high formability, such as the automotive industry, providing good oxidation and corrosion resistance for exhaust system components including mufflers, pipes, and catalytic converters, as well as residential furnace primary heat exchanger and sugar industry applications as examples.

Note that it can be work-hardened slightly to increase tensile strength and is not subject to Chloride stress corrosion cracking. It is often used where high thermal conductivity is required.

439 Stainless Steel Properties

The high Chromium content of this stainless steel makes it highly resistant to pitting corrosion and, like all ferritic grades, it is not susceptible to stress corrosion.  Titanium alloying of 439 stainless steel plate reduces its sensitivity to intergranular cracking and the high Chromium content also improves resistance to crevice corrosion making it superior to some other ferritic stainless steels for certain applications.

Oxidation resistance of 439 is good up to 1760°F (950°C). In environments containing Chloride, pitting and crevice corrosion are possible depending on things such as Chloride concentration, temperature, pH value, and redox potential. In these environments, obtaining optimal performance from stainless steel alloy 439 requires efficient design, correct post-weld treatment and, when applicable, regular cleaning.

At ESM-Hampshire, 439 stainless steel can be readily cold-formed by all standard processes and is particularly suitable for deep drawing making the alloy comparable in its deep drawing ability to the deep drawing quality steels. However, its lower work-hardening rate compared to standard austenitic grades, makes it less suitable for applications involving stretch forming.

That same quality of a lower work hardening rate makes it more easily cold formed and machined with similar forces needed in cold-forming and machining necessary for low-alloyed Carbon steels.

Stainless steel 439 produced by ESM-Hampshire Mill has low C and N contents and is stabilized with titanium, which reduces or prevents the formation of martensite. This stabilization gives 439 better weldability than many other ferritic steels. Our process keeps heat input at a minimum to limit grain growth in the heat affected zone.

Applications of 439 Stainless Steel

439 stainless steel was developed in the 1950s. It was developed for use in direct-fired water heater tanks. This application required good welding properties and stress corrosion cracking resistance. Currently in the United States, lower cost immersion equipment and glass-lined tanks have replaced 439, which continues to be used successfully in Europe for direct fired hot water tanks.

The major advantages of 439 alloy are:

1. Excellent resistance to Chloride stress corrosion cracking
2. Good general corrosion resistance particularly in fresh waters and mildly oxidizing environments
3. Excellent welding properties
4. High thermal conductivity coefficient
5. Low thermal expansion coefficient
6. Reflective color compatibility
7. Good continuous & cyclic oxidation resistance
8. Long-term cost advantages.

The use of the Argon Oxygen Decarburization (AOD) process has improved many stainless steel alloys, including 439, by providing an efficient method for removing Carbon and Sulfur with minimum losses of Chromium. Therefore, 439 stainless steel plate is now used widely in a variety of applications including the power generation, petroleum refining, and chemical process industries. Heat exchanger tubing made of 439 stainless steel is the choice in the residential furnace market, some small hot water tank applications, and automotive exhaust manifolds and mufflers.

At ESM, we pride ourselves on our ability to deliver in accordance with our customers’ specifications and timelines. We are also continually improving both our products and our processes so that we can stay current and remain competitive. To do this, we ensure that we are current in our tool implementations as well as recognizing the need to invest in the future by keeping our employees current with and trained for the latest industry technologies as we implement them.

We are committed to not just meeting but exceeding our customer’s expectations by undertaking jobs with short lead times and delivering them on time. Contact us as 800-323-0758 to speak to one of our experienced professionals.

**The information and data in this product data sheet are accurate to the best of our knowledge and belief, but are intended for general information only.  Applications suggested for the materials are described only to help readers make their own evaluations and decisions, and are neither guarantees nor to be construed as express or implied warranties of suitability for these or other applications. Data was obtained from our melt sources with data referring to mechanical properties and chemical analyses are the result of tests performed on specimens obtained from specific locations with prescribed sampling procedures; any warranty thereof is limited to the values obtained at such locations and by such procedures. There is no warranty with respect to values of the materials at other locations.  Further information should be sought from the melt sources.