Alloy 304 & 304L Stainless steel
The world’s most common stainless steel.
Applications
Very wide ranging. It is practically used almost everywhere – pressure vessels, heat exchangers, pumps and valves, food and wine industry, pharmaceutical industry, cryogenic industry, power industry etc.
Properties
Alloy 304/304L is standard 18-8 stainless steel (18% Chromium and 8% Nickel) that is used for a wide range of general purpose applications. The alloy has a good corrosion resistance in a wide range of atmospheric conditions as well as moderately oxidizing and reducing environments.
304/304L has excellent forming and welding characteristics. It also has an excellent resistance to intergranular corrosion in as-welded condition. Dual grade becomes important if heavy gauge welding is performed. This is where intergranular corrosion comes into picture and having a lower carbon version makes it difficult for Chromium Carbide to precipitate in the 797 to 1580 degF (425 to 860 degC) range when the welding is going on for a long time due to the heavy gauge. Finally, it has excellent strength and toughness at cryogenic temperatures.
In warm chloride environments, it is prone to pitting and crevice corrosion and also to stress corrosion cracking above 140 degF (60 degC).
Specifications
Chemistry/304
C – 0.08 max
Mn – 2 max
P – 0.045 max
S – 0.03 max
Si – 1 max
Cr – 18 to 20
Ni – 8 to 11
Chemistry/304L
C – 0.035 max
Mn – 2 max
P – 0.045 max
S – 0.03 max
Si – 1 max
Cr – 18 to 20
Ni – 8 to 11
Mechanical Properties
Both 304 and 304L have the same mechanical properties.
304/304L
Yield Strength – 205 MPa minimum
Tensile Strength – 515 MPa minimum
% elongation – 35% minimum (longitudinal)
Common specifications
Pipes – SA/A312, SA/A358
Fittings – SA/A403
Flanges/ Forgings – SA/A182
Tubes – SA/A213, SA/A249, SA/A269
Bars – SA/A276
Plates – SA/A240
As one can see from the above the dual grade 304/304L should have a C of 0.035 max.
| Type | Sizes | Schedules | ASTM Standards |
|---|---|---|---|
| Bar | A276, A479 | ||
| Butt Weld Fittings | 1/2″ thru 12″ | Sch 10, 40, 80, 160 & XXH | A403 |
| Forgings | 1/2″ thru 8″ | A182 | |
| Pipe Welded & Seamless | 1/4″ thru 16″ | Sch 10, 40, 80, 160 & XXH | A312 |
| Tube, Welded | A249 | ||
| Tube, Seamless | A213 | ||
| Plate | A240 | ||
| Flange & Pressure Fittings | All Descriptions |