|
|
Features
* Excel lent oxidization resistance
through 2000'F
* High creep-rupture strength
* Excellent resistance to thermal
shock
* Good weldability
Applications
* Pulverized coal burners in power
boilers
* Recuperators
* Petrochemical, refinery and steam
superheater tube hangers
* Radiant heating tubes for steel and
aluminum annealing
* Steel mill annealing inner covers
* Thermal oxidizers
* Expansion bellows
* Furnace fans, dampers
* Fluidized combustor cyclones
* Kilns
Nominal Chemical Composition
|
element
|
weight %
|
|
Nickel
|
11
|
|
Chromium
|
21
|
|
Manganese
|
0.6
|
|
Silicon
|
1.7
|
|
Carbon
|
0.08
|
|
Nitrogen
|
0.17
|
|
Cerium
|
0.04
|
|
Iron
|
65
|
Specifications
UNS S30815
ASTM A 240, A 276, A 479, A 312, A
249
ASME SA-240, SA-479, SA-312, SA-249,
Code Case 2033-1
|
|
Performance Profile
RA253MA is a lean austenitic heat resistant
alloy with high strength and outstanding oxidation
resistance. RA 253 MA obtains its heat resistant
properties by advanced control of micro alloy
additions.
The use of rare earth metals in combination with
silicon gives superior oxidation resistance to 2000
°F. Nitrogen, carbon and a dispersion of rare
earth and alkali metal oxides combine to provide
creep rupture strength comparable to the nickel
base alloys.
RA253MA has only fair resistance to
carburization. A better combination of strength and
carburization resistance is offered by RA85H.
Austenite stability in RA253MA is enhanced by
the nitrogen addition, so that formation of
embrittling sigma phase is retarded. Material
tested after aging 5000 hours at 1472 °F has
retained 16 ft-lb. Charpy V-Notch impact
strength.
RA253MA is welded using matching composition
RA253MA AC/DC covered electrodes and bare wire.
GMAW shielding gas may be 100% argon. Improved
wetting and bead contour may be had with a mix of
80% minimum argon, 18% maximum helium and 2%
maximum CO2. For short-circuiting arc transfer 68%
Ar 30% He 2% CO2 has been satisfactory.
Mechanical Properties
Representative Tensile Properties
|
Temp °F
|
Ultimate Tensile Strength,
psi
|
0.2% Yield Strength, psi
|
Elongation %
|
Reduction of Area, %
|
|
68
|
102,000
|
51,600
|
51
|
68
|
|
1292
|
56,400
|
23,000
|
44
|
58
|
|
1562
|
24,800
|
14600
|
-
|
88
|
Typical Creep-Rupture Properties
|
Temp °F
|
Stress, psi, for a Secondary Creep
Rate of 1% in 10,000 hrs
|
Rupture Strength, psi 10,000 hrs
100,000 hrs
|
|
1400
|
5000
|
5200
|
2900
|
|
1600
|
2300
|
2500
|
1450
|
|
1800
|
890
|
1150
|
700
|
Physical Properties
|
Density lb/in3
0.282
|
Melting Range °F
2500-2610
|
|
Temp °F
|
Coefficient* of Thermal Expansion,
in/in°F x 10-6
|
Modulus of Thermal Conductivity
Btu•ft/fl2•hr•°F
|
Elasticity Dynamic, psi x
106
|
|
70
|
-
|
8.38
|
29.0
|
|
1400
|
10.3
|
14.0
|
20.2
|
|
1600
|
10.5
|
15.3
|
-
|
|
1800
|
10.8
|
16.6
|
17.6
|
* 70 °F to indicated temperature.
For more information on RA 253 MA request Bulletin
126.
Welding is covered in Bulletin 202.
|