SX
304 / 304L Technical Data
Summary
SX
304 is the most versatile and the most
widely used of all stainless steels. Its chemical
composition, mechanical properties, weldability and corrosion/oxidation
resistance provide the best all-round performance stainless
steel at relatively low cost. It also has excellent
low temperature properties and responds well to hardening
by cold working. If intergranular corrosion in the
heat affected zone may occur, it is suggested that SX
304L be used.
Typical
Applications
SX
304 is used in all industrial, commercial and domestic
fields because of its good corrosion and heat resisting
properties. Some applications include:
Tanks and containers for a large variety of liquids and
solids.
Process
equipment in the mining, chemical, cryogenic, food, dairy
and pharmaceutical industries.
Chemical
Composition (ASTM A240)
| SX |
oC |
Mn |
P |
S |
Si |
Cr |
Ni |
304
304L |
0.08
max
0.03 max |
2.0
max |
0.045
max |
0.030
max |
1.0
max |
18.0
to
20.0 |
8.0
to 10.50
8.0 - 12.0 |
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
| |
304 |
304L |
| Typical |
Minimum |
Typical |
Minimum |
| Tensile
Strength, MPa |
600 |
515 |
590 |
485 |
| Proof Strength,
(Offset 0.2 %), MPa |
310 |
205 |
310 |
170 |
| Elongation
(Percent in 50mm) |
60 |
40 |
60 |
40 |
| Hardness
(Brinell) |
170 |
- |
170 |
- |
| Endurance
(fatigue) limit,
MPa |
240 |
- |
240 |
- |
2. Properties at elevated
temperatures
All these
values refer to 304 only.
304L values are not given
because its strength decreases markedly above 425oC.
Time Elevated Temperature
Tensile Strength
| Temperature,
oC |
600 |
700 |
800 |
900 |
1000 |
| Tensile
Strength, MPa |
380 |
270 |
170 |
90 |
50 |
Creep data Stress
for a creep rate of 1% in 10 000 h.
| Temperature,
oC |
550 |
600 |
650 |
700 |
800 |
| Stress,
MPa |
120 |
80 |
50 |
30 |
10 |
Maximum Recommended Service
Temperature
(Oxidising Conditions)
Continuous
Service
925oC
Intermittent Service
850oC
3.
Properties at Sub-Zero Temperatures
( SX
304 / 304L )
| Temperature |
oC |
-78 |
-161 |
-196 |
| Tensile
Strength |
MPa |
1100/950 |
1450/1200 |
1600/1350 |
| Proof Stress
(Offset 0.2%) |
MPa |
300/180 |
380/220 |
400/220 |
| Impact
Strength (Charpy V-Notch) |
J |
180/175 |
160/160 |
155/150 |
4. Corrosion Resistance
Aqueous
As a rough guide the following
examples are given for certain pure acid-water mixtures-
| Temperature
oC |
20 |
80 |
| Concentration,
% by mass |
10
20 40
60 80
100 |
10
20 40
60 80
100 |
| Sulphuric
Acid |
2
2 2
2
1
0 |
2
2 2
2 2
2 |
| Nitric
Acid |
0
0 0
0
2
0 |
0
0 0
0 1
2 |
| Phosphoric
Acid |
0
0 0
0
0
2 |
0
0 0
0 1
2 |
| Formic
Acid |
0
0 0
0
0
0 |
0
1 2
2 1
0 |
Key:
0 = resistant - corrosion
rate less than 100 mm/year
1 = partly resistant -
corrosion rate 100m to 1000 mm/year
2
= non resistant - corrosion rate more
than 1000 mm/year
4.2 Atmospheric
The
performance of SX 304 compared with other metals in various
environments is shown in the following table. The corrosion
rates are based on a 10 year exposure.
| Environment |
Corrosion
Rate (mm/year) |
| SX 304 |
Aluminium-3S |
Mild Steel |
| Rural |
0.0025 |
0.025 |
5.8 |
| Marine |
0.0076 |
0.432 |
34.0 |
| Marine
Industrial |
0.0076 |
0.686 |
46.2 |
Thermal
Processing
1.
Annealing. Heat from 1010oC to 1120oC and cool
rapidly in air or water. The best corrosion resistance
is obtained when
the final annealing is above 1070oC and cooling
is rapid.
2.
Stress relieving. SX 304L can be stress relieved
at 450-600oC for one hour with little danger
of sensitisation.
A lower stress relieving temperature of 400oC
maximum must be used.
3.
Hot working
Initial forging and pressing:
1150 to 1260oC
Finishing temperature:
900 to 925oC
All
hotworking operations should be followed by annealing.
Note:
Soaking times to ensure uniformity of temperature are
longer for stainless steels than for carbon steels - approximately
12 times.
Cold
Working
SX
304 / 304L being extremely tough and ductile, are readily
fabricated by old working. Typical operations include
bending, forming, deep drawing and upsetting
