439 1.4510 (also known as ASTM XM-8) is a ferritic stainless steel designed to resist corrosion in a variety of oxidizing environments from fresh water to boiling acids.

Applications

Type 439 Stainless Steel is attractive for numerous automotive exhaust applications. Typical uses include tubular manifolds and other exhaust system components where temperatures may exceed the oxidation limit of Type 409, or where wet corrosion resistance, particularly to chlorides, is needed.

Equivalent

Chemical Composition:

Mechanical Properties:

Sizes

Hot Rolled Process – OD 30-500mm ; WT 3-60mm ; L 6-12meter

Cold Drawn Process – OD 10-200mm ; WT 0.5-20mm ; L 1-12meter

Cold Rolled Process – OD 6-200mm ; WT 0.1-20mm ; L 1-12meter

Surface

Acid pickling – pre-passivation process of treating stainless steel parts with an acid solution, typically hydrochloric or sulfuric acid, which can remove oxide scale and heat tint while dissolving steel flecks embedded in the part.

Polishing – P grade sandpaper: P150, P200, P250, P300, P400, P500, P600, P700, P800

Inspection

Chamical analysis / Tensile test at room temperature / flattening test / ring tensile test / drift expemdomg test / ring expanding test / leak tightness test / Tensile test at elevated temperature / impact test at room temperature / impact test at low temperature / eddy current test / ultrasonic test / magnetic flux leakage test

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.

Forming:

Type 439 provides good formability. Olsen Cup heights of 0.490″ are obtainable, flat bends of 180° are possible with material up to 0.080″ thick.

Welding:

Type 439 is generally considered to be weldable by the common fusion and resistance techniques. It has weldability comparable to Type 409 stainless steel.