STAINLESS STEEL 304 / 304L Technical Data
Stainiless steel 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 SS 304L be used.
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)
|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
|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|
|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
|Tensile Strength, MPa||380||270||170||90||50|
Creep data Stress for a creep rate of 1% in 10 000 h.
Maximum Recommended Service Temperature
Continuous Service 925oC
Intermittent Service 850oC
3. Properties at Sub-Zero Temperatures
( SX 304 / 304L )
|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
As a rough guide the following examples are given for certain pure acid-water mixtures-
|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
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|
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.
SS 304 / 304L being extremely tough and ductile, are readily fabricated by old working. Typical operations include bending, forming, deep drawing and upsetting