439 STAINLESS STEEL ALLOY

Description

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.

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.

Physical Properties:

• Melting Point: 2741°F (1505°C)
• Density: 0.278 lbs/in3 / 7.70 g/cm3
• Modulus of Elasticity in Tension: 28 X 106 psi / 193 GPa

Mechanical Properties:

• Tensile Strength Minimum (psi): 66,000 - 70,000
• Yield Strength Minimum 0.2% offset (psi): 43,000 - 48,000
• % Elongation in 2” Minimum: 32 - 36%
• Hardness: Rockwell B74 - 78

Composition:

• Carbon: 0.025 max
• Manganese: 0.50
• Silicon: 0.75
• Chromium: 17.00 - 19.00
• Nickel: 0.50
• Titanium: ≥ 0.20+4(C+N)min - 0.50 max
• Iron: Balance
• All values are maximum values unless otherwise specified. Values derived from applicable AMS and ASTM specifications.

Heat Treatments: Type 439 is not hardenable by heat treatment

• Annealing:
• Heat slowly to 1450 -1600°F (790 - 871°C), quickly cool. Slow cooling produces less desirable impact transition behavior. Ferritic stainless steels containing more than about 12% chromium have a susceptibility to a phenomenon known as 885°F (475°C) embrittlement. This embrittlement is observed as a degradation of impact properties at room temperature resulting from very long exposures in the temperature range of 700 to 1000°F (371 to 537°C). If service temperatures are cycling through this range, exposure above, about 1050°F (565°C), restores the room temperature toughness properties. When there have been long dwell times near 885°F (475°C), service temperatures that cycle above, about 1050°F (565°C), are beneficial rather than detrimental.

Corrosion Resistance:

AISI Type 439 is resistant to attack by potable water and many mildly or moderately corrosive chemical environments which are oxidizing in nature. In various chloride solutions, studies have shown pitting resistance of Type 439 to be superior to that of Type 304. In addition, Type 439 is not subject to stress corrosion cracking which may cause premature failure of austenitic steels in chloride bearing environments such as hot waters used in heat exchangers.

Our Production Machinery

Applications of Stainless Steel Strip:

Stainless steel strip for tube/pipe making
Stainless steel strip for building material, kitchen sinks/cutlery, baths, elevators
Stainless steel strip for kitchen benches
Stainless steel strip for automotive application
Stainless steel strip for metal stamping
Stainless steel strip for industrial application, hose, hardware-tools
Stainless steel strip for spring applications
Stainless steel strip for cable industry, ropes, etc