309 is an austenitic heat resistant alloy with oxidation resistance to 1900°F under constant temperature conditions. When frequent thermal cycling is involved, the alloy is resistant to about 1850°F. The high chromium and relatively low nickel content of 309 provide good resistance to high temperature sulfur bearing atmospheres. 309 has only moderate resistance to carbon absorption and is not suggested for use in highly carburizing atmospheres.
Often in many product forms, the grain size and carbon content can meet both the 309S and 309H requirements. Prolonged exposure to the 1100-1600°F temperature range will cause some sigma to form, lowering room temperature ductility and impact resistance. Should sigma formation be anticipated, care should be taken to avoid heavy mechanical impact at room temperature. 309 has a machinability rating of 43% relative to AISI B1112 steel. Room temperature forming is suggested. Weld with AWS E309-16 covered electrodes or ER309 bare wire.
Chemistry
|
|
Cr
|
Ni
|
C
|
P
|
S
|
Mn
|
Fe
|
|
MIN
|
22.0
|
12.0
|
-
|
-
|
-
|
-
|
-
|
|
MAX
|
24.0
|
15.0
|
0.08
|
0.045
|
0.03
|
2.0
|
Balance
|
Specifications
Inventory
309 Pipe, 309 Plate, 309 Rod Coil, 309 Sheet, 309 Weld Wire
Common Trade Names
309 Stainless
Features
· Oxidation resistant to 1900°F
· Moderate strength at high temperature
· Ease of fabrication
· Good sulfidation resistance
· Good weldability
Applications
· Annealing covers and boxes
· Carbon saggers
· Waste incinerators
· Pulverized coal burners
· Brazing fixtures
· Lead pans, neutral salt pots
· Muffles, retorts
· Furnace fans and shafts
· Radiant tubes for aluminum and steel annealing
· Glass forming equipment
· Thermowells
· Paper mill equipment
· Power boiler tube hangers
· Rotary kilns and calciners
· Anchor bolts
Physical Properties
Density: 0.285 lb/inch3
Melting Point: 2500 - 2590°F
|
Temperature, °F
|
70
|
1000
|
1200
|
1400
|
1600
|
|
Coefficient* of Thermal Expansion, in/in°F x 10-6
|
-
|
9.7
|
-
|
-
|
10.1
|
|
Thermal Conductivity, Btu • ft/ft2 • hr • °F
|
7.4
|
11.5
|
12.4
|
-
|
-
|
|
Modulus of Elasticity, Dynamic psi x 106
|
28.5
|
22.5
|
21.0
|
19.5
|
18.0
|
* 70°F to indicated temperature.
Mechanical Properties
Representative Tensile Properties
|
Temperature, °F
|
70
|
1200
|
1600
|
|
Ultimate Tensile Strength, ksi
|
90
|
52
|
18
|
|
0.2% Yield Strength, ksi
|
45
|
22
|
-
|
|
Elongation, %
|
50
|
26
|
32
|
Typical Creep- Rupture Properties
|
Temperature, °F
|
1200
|
1400
|
1600
|
1800
|
|
Minimum Creep 0.0001%/Hr, ksi
|
16
|
3.4
|
1.4
|
0.22
|
|
10,000 Hour Rupture Strength, ksi
|
17.2
|
4.8
|
1.6
|
0.56
|
