What are the Differences Between Alloy 304 and 304L Stainless Steel?

Alloy 304 and 304L Stainless Steel Specification
ASTM: A240, A312, A376, A358, A269, A249, A403, A182, A351
ASME : SA240, SA312, 5A376, SA358, SA269, SA249, SA403, SA182, SA351

What are the Differences Between Alloy 304 and 304L?

Alloy 304 is the most widely used austenitic (non-magnetic) stainless steel. It is also known as "18/8" stainless steel because of its composition, which includes 18 percent chromium and 8 percent nickel. Alloy 304 stainless steel has good forming and welding properties as well as strong corrosion resistance and strength.
Alloy 304L stainless steel is an extra-low carbon version of the 304 steel alloy. The lower carbon content in 304L minimizes deleterious or harmful carbide precipitation as a result of welding. Alloy 304L can, therefore, be used "as welded" in severe corrosion environments, and it eliminates the need for annealing.
Alloy 304 and 304L Stainless Steel Chemical Analysis (by weight):

Element	Type 304 (%)	Type 304L (%)
Carbon	0.08 max.	0.03 max.
Manganese	2.00 max.	2.00 max.
Phosphorus	0.045 max.	0.045 max.
Sulfur	0.03 max.	0.03 max.
Silicon	0.75 max.	0.75 max.
Chromium	18.00-20.00	18.00-20.00
Nickel	8.00-10.50	8.00-12.00
Nitrogen	0.10 max.	0.10 max.

Alloy 304 and 304L Stainless Steel Application

Alloy 304 stainless steel has good drawability. It can be formed into a variety of shapes and, in contrast to type 302 stainless, can be used without annealing. Common uses for type 304 stainless steel are found in the food industry. It's ideal for brewing, milk processing and wine-making, as well as for pipelines, yeast pans, fermentation vats and storage tanks.​
Alloy 304 grade stainless steel is also found in sinks, tabletops, coffee pots, refrigerators, stoves, utensils and other cooking appliances. It can withstand corrosion that can be caused by various chemicals found in fruits, meat and milk. Other areas of use include architecture, chemical containers, heat exchangers, mining equipment, as well as marine nuts, bolts and screws. Type 304 is also used in mining and water filtration systems and in the dyeing industry.
Alloy 304L grade stainless steel has slightly lower mechanical properties than the standard 304 grade, but is still widely used thanks to its versatility. Like alloy 304 stainless steel, it's commonly used in beer-brewing and wine-making, but also for purposes beyond the food industry such as in chemical containers, mining and construction. It is ideal for use in metal parts such as nuts and bolts that are exposed to salt water.  
 

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