Physical Properties
Typical physical properties for annealed grade 304
stainless steels are given in table 3.
Table
3. Physical properties of 304 grade stainless steel in the annealed
condition
|
|
|
|
|
|
|
|
|
|
|
|
304/L/H |
8000 |
193 |
17.2 |
17.8 |
18.4 |
16.2 |
21.5 |
500 |
720 |
Grade Specification Comparison
Approximate grade comparisons for 304 stainless
steels are given in table 4.
Table
4. Grade specifications for 304 grade stainless steel
|
|
|
|
|
|
|
|
|
|
304 |
S30400 |
304S31 |
58E |
1.4301 |
X5CrNi18-10 |
2332 |
SUS 304 |
304L |
S30403 |
304S11 |
- |
1.4306 |
X2CrNi19-11 |
2352 |
SUS 304L |
304H |
S30409 |
304S51 |
- |
1.4948 |
X6CrNi18-11 |
- |
- |
These
comparisons are approximate only. The list is intended as a
comparison of functionally similar materials not as a
schedule of contractual equivalents. If exact equivalents
are needed original specifications must be consulted. |
Possible Alternative Grades
Possible alternative
grades to grade 304 stainless steels are given in table 5.
Table 5. Possible alternative grades to
304 grade stainless steel
|
|
301L |
A higher work hardening rate grade is required for certain
roll formed or stretch formed components. |
302HQ |
Lower work hardening rate is needed for cold forging of
screws, bolts and rivets. |
303 |
Higher machinability needed, and the lower corrosion
resistance, formability and weldability are acceptable. |
316 |
Higher resistance to pitting and crevice corrosion is
required, in chloride environments |
321 |
Better resistance to temperatures of around 600-900¢XC is
needed¡K321 has higher hot strength. |
3CR12 |
A lower cost is required, and the reduced corrosion
resistance and resulting discolouration are acceptable. |
430 |
A lower cost is required, and the reduced corrosion
resistance and fabrication characteristics are acceptable. |
Corrosion Resistance
Excellent in a wide range
of atmospheric environments and many corrosive media. Subject to pitting
and crevice corrosion in warm chloride environments, and to stress
corrosion cracking above about 60¢XC. Considered resistant to potable
water with up to about 200mg/L chlorides at ambient temperatures,
reducing to about 150mg/L at 60¢XC.
Heat Resistance
Good oxidation resistance
in intermittent service to 870¢XC and in continuous service to 925¢XC.
Continuous use of 304 in the 425-860¢XC range is not recommended if
subsequent aqueous corrosion resistance is important. Grade 304L is more
resistant to carbide precipitation and can be heated into the above
temperature range.
Grade 304H has higher
strength at elevated temperatures so is often used for structural and
pressure-containing applications at temperatures above about 500¢XC and
up to about 800¢XC. 304H will become sensitised in the temperature range
of 425-860¢XC; this is not a problem for high temperature applications,
but will result in reduced aqueous corrosion resistance.
Heat Treatment
Solution Treatment (Annealing) - Heat to 1010-1120¢XC and cool
rapidly. These grades cannot be hardened by thermal treatment.
Welding
Excellent weldability by
all standard fusion methods, both with and without filler metals. AS
1554.6 pre-qualifies welding of 304 with Grade 308 and 304L with 308L
rods or electrodes (and with their high silicon equivalents). Heavy
welded sections in Grade 304 may require post-weld annealing for maximum
corrosion resistance. This is not required for Grade 304L. Grade 321 may
also be used as an alternative to 304 if heavy section welding is
required and post-weld heat treatment is not possible.
Machining
A "Ugima" improved
machinability version of grade 304 is available in bar products. "Ugima"
machines significantly better than standard 304 or 304L, giving higher
machining rates and lower tool wear in many operations.
Dual Certification
It is common for 304 and
304L to be stocked in "Dual Certified" form, particularly in plate and
pipe. These items have chemical and mechanical properties complying with
both 304 and 304L specifications. Such dual certified product does not
meet 304H specifications and may be unacceptable for high temperature
applications.
Stainless steel 304L,
316L flange and pipe
carbon steel
304L,316L flange and pipe fittings
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