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Features
* Oxidization resistance to 2200~F
* Sulfidation resistance
* High thermal conductivity
* Resistance to molten copper
* Low strength
Applications
* Recuperators
* Spouts for conveying molten copper
alloys
* Oil burner parts
* Combustion chambers
* Furnace and kiln linings
* Stack dampers
* Neutral salt pot electrodes
* Boiler baffles
* Glass molds
Nominal Chemical
Composition
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element
|
weight %
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Chromium
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25
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Manganese
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0.7
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Silicon
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0.5
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Nitrogen
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0.1
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Carbon
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0.05
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Iron
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73
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Specifications
UNS S44600
ASTM A 176, A 276
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Performance Profile
RA446 is a high chromium ferritic heat resistant
alloy with excellent resistance to oxidation,
sulfidation and other forms of hot corrosion. This
grade is most commonly used between 1500 and 2200
°F, although its elevated temperature strength
is quite low. RA446 is the only heal resistant
alloy that will tolerate molten copper and brass.
As with other high chromium ferritic stainlesses,
RA446 embrittles severely in the 700-1000
temperature range (885 °F embrittlement).
RA446 should not be used in this temperature range
unless nearly complete loss of room temperature
ductility may be tolerated. Sigma phase
embrittlement occurs upon long time exposure in the
range 1000-1300 °F. RA446 has a high
ductile-to-brittle impact transition temperature.
Therefore, successful forming and bending is aided
by low forming speeds, edge preparation and
preheating to 250-400 °F. Annealing, when
necessary, should be performed at 1550-1650
°F, rapid cool. Welding may be accomplished by
conventional methods. Preheating and postheating to
300-600 °F is helpful. Austenitic weld
fillers, such as RA310 or AWS E312 are generally
suggested to maximize weld deposit ductility.
Mechanical Properties
Typical Room Temperature Properties
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Tensile Strength, psi
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0.2% Yield Strength, psi
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Elongation %
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Hardness Rb
|
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77,000
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50,000
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30
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83-93
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Typical Creep-Rupture Properties
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Temp °F
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Stress, psi, for a Secondary Creep
Rate 1% in 10,000 hrs
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10,000 hr Rupture Strength,
psi
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1400
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260
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1,100
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1600
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-
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450
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1800
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-
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230
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Physical Properties
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Density lb/in3
0.270
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Melting Range °F
2640-2710
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Temp °F
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Coefficient* of Thermal Expansion,
in/in°F x 10-6
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Thermal Conductivity
Btu•fl/ft2•hr•°F
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Modulus of Elasticity Dynamic, psi
x 106
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70
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-
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13.2
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30.4
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1200
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6.3
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18.8
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20.0
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1400
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6.4
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19.9
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-
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1600
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6.7
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20.8
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-
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1800
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7.3
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21.6
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-
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* 70 °F to indicated temperature.
For more data on RA446 request Bulletin 123.
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