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Summary
SX309 is a highly alloyed austenitic stainless steel
used for its excellent oxidation resistance, high
temperature strength and creep resistance. The
lower nickel content of SX309 improves resistance to
sulphur attack at high temperatures. It is tough
and ductile, and can be readily fabricated and
machined. SX 309S is the low-carbon version of
SX 309, and is recommended for applications where
sensitisation, and subsequent corrosion by high
temperature gases or condensates during shutdown may
pose a problem.
SX 309 is manufactured to ASTM A 167 and SX 309S to
ASTM A240 specifications.
Typical
Applications
SX 309/309S is used exclusively for its high
temperature oxidation resistance. It is common
for SX 309, 310 and 321 to be used in the same piece
of equipment in the various temperature regions.
Chemical
Composition (SATM A240)
|
SX
|
C
|
Mn
|
P
|
S
|
Si
|
Cr
|
Ni
|
|
309
309S
|
0.20
max
0.08 max
|
2.00
max
|
0.045
max
|
0.030
max
|
1.00
max
|
22.0
-
24.0
|
12.0
-
15.0
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Typical Properties in the
Annealed Condition
The properties quoted in this publication are typical
of mill production and unless indicated should not be
regarded as guaranteed minimum values for
specification purposes.
1.
Mechanical Properties at Room Temperature
|
|
SX
309
|
SX
309S
|
|
|
TYPICAL
|
MIN
|
TYPICAL
|
MIN
|
|
Tensile
Stength
MPa
|
560
|
515
|
540
|
515
|
|
Proof
Stress (0.2%
Offset)
MPa
|
285
|
205
|
280
|
205
|
|
Elongation
(Percent in 50 mm)
|
54
|
40
|
54
|
40
|
|
Hardness
(Brinell)
|
164
|
|
159
|
|
|
Endurance
(fatigue)
limit
MPa
|
260
|
|
260
|
|
2.
Properties at Elevated Temperatures
The values quoted are those for SX 309
Short Time Elevated Temperature Tensile Stress
|
Temperature
|
oC
|
550
|
650
|
750
|
850
|
950
|
1
050
|
|
Tensile
Stress
|
MPa
|
440
|
360
|
240
|
150
|
70
|
30
|
Creep
Data
Stress to develop a creep rate of 1% in the time
indicated at the temperature indicated.
|
Time
|
TemperatureoC
|
550
|
600
|
650
|
700
|
750
|
800
|
|
10
000 h
100 000 h
|
Stress
MPa
Stress MPa
|
100
75
|
80
50
|
60
30
|
30
20
|
25
10
|
10
5
|
Creep
Rupture Stress
|
Time
|
Temperature
oC
|
600
|
700
|
800
|
900
|
1
000
|
|
1
000 h
10 000 h
100 000 h
|
Stress
MPa
Stress MPa
Stress MPa
|
180
150
100
|
90
50
40
|
35
30
20
|
20
10
5
|
5
2
-
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Maximum
Recommended Service
Temperature
(Oxidising Conditions)
Continuous
1 100oC
Intermittent
980oC
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Thermal
Processing
Annealing. Heat between 1 050oC
and 1 150oC and water quench.
This treatment ensures that all carbides are in
solution.
-
Stress
Relieving 250-400oC for 1
hour.
-
Hot
Working
Initial forging and pressure:- 1 150-1 200oC
Finishing temperature:- 1 000oC
Note:
Soaking times to ensure uniformity of temperature are
up to 12 times that required for mild and carbon
steels.
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