SX
321 Technical Data
Summary
SX
321 is a titanium-stabilised version of SX 304,
used in particular applications within the sensitizing
temperature range. Its resistance to sensitization,
coupled with its higher strength at high temperature makes
it suitable in application where SX 304 will become sensitized,
or where SX 304L has insufficient hot strength.
It is not subject to weld decay (intergranular corrosion)
when exposed to mildly corrosive environments. However,
welded SX 321 must never be used in highly oxidising environments
as it is liable to 'Knife-line' attack.
Typical
Applications
SX
321 is today used almost exclusively for service within
the sensitizing temperature range (450-850oC).
In welded ambient temperature applications it has been
replaced by SX 304L. Some typical areas of application
are:
Furnace components.
Superheater and afterburner parts.
Compensators and expansion bellows.
Chemical
Composition (ASTM A240)
| |
C |
Mn |
P |
S |
Si |
Cr |
Ni |
Ti |
| SX Analysis |
0.08 max |
2.0 max |
0.045 max |
0.030 max |
1.0 max |
17.0 -
19.0 |
9.0 - 12.0 |
5X%C min
0.5 max |
| Typical |
0.06 |
1.2 |
0.020 |
0.020 |
0.5 |
17.5 |
9.4 |
0.48 |
Typical
Properties in the Annealed Condition
The
properties quoted in this publication are typical of mill
products. Unless otherwise indicated they should
not be regarded as guaranteed minimum values for specification
purposes.
1.
Mechanical Properties at Room Temperature
| |
Typical |
Minimum |
| Tensile
Strength, MPa |
580 |
515 |
| Proof Stress
(0.2 % offset), MPa |
280 |
205 |
| Elongation
(Percent in Lo = 5.65 So) |
60 |
40 |
| Hardness
(Brinell) |
163 |
- |
| Endurance
(fatigue) limit, MPa |
260 |
- |
2.
Properties at Elevated Temperatures
Short Time Elevated Temperature
Tensile Strength
| Temperature,
oC |
600 |
650 |
700 |
750 |
800 |
850 |
| Tensile
Strength, MPa |
390 |
329 |
280 |
230 |
190 |
140 |
Creep
data
Stress to develop a creep
rate of 1% in the indicated time at the indicated temperature.
| Time |
Temperature
oC |
550 |
600 |
650 |
700 |
800 |
| 10 000
h |
Stress
MPa |
180 |
100 |
70 |
40 |
10 |
| 100 000
h |
Stress
MPa |
120 |
80 |
50 |
25 |
5 |
Creep
Rupture Stress
| Time |
Temperature
oC |
500 |
600 |
650 |
700 |
800 |
| 1 000 h |
Stress
MPa |
270 |
180 |
140 |
70 |
30 |
| 10 000
h |
Stress
MPa |
240 |
130 |
90 |
50 |
10 |
| 100 000
h |
Stress
MPa |
200 |
90 |
50 |
15 |
5 |
Recommended
Maximum Service Temperature
(Oxidising Conditions)
Continuous
Service
950oC
Intermittent Service
870oC
Thermal
Processing
1. Annealing
Heat from 1050 to 1150oC and cool
in air. This ensures maximum ductility of the steel.
2. Stress
Relieving SX 321 can be stress-relief annealed within
the sensitization temperature range
450-800oC without carbide precipitation occurring,
thus avoiding the possibility of intergranular corrosion.
3.
Hot working
Initial forging and pressing temperature:
1150 - 1250oC
Finishing temperature:
950oC
Note: Soaking times
to ensure uniformity of temperature are up to 12 times that required for carbon steel. Care
must be exercised with this grade, and long soaking times
to ensure even distribution of carbides should be employed.
The initial reductions must be light to allow dispersion
of carbides in the flow pattern during forging.
