Stainless steel is an alloy material with excellent corrosion resistance and is widely used in various industrial and civil fields. Among them, 304 and 304L are the two most common types of stainless steel, both of which are austenitic stainless steel. 304L stainless steel is a low-carbon version of 304 stainless steel with better welding performance and resistance to intergranular corrosion. Although 304 stainless steel and 304L stainless steel have similar chemical composition and properties, there are still some differences in some aspects. Next, let’s take a look at them together!
304 stainless steel is an austenitic stainless steel containing chromium and nickel. Its main components are 18% chromium and 8% nickel, so it is also called 18/8 stainless steel.
Excellent corrosion resistance: 304 stainless steel shows good corrosion resistance in the atmosphere, fresh water and many chemical environments.
Good mechanical properties: 304 stainless steel has high strength and toughness and can withstand large mechanical stress.
Ease of processability: 304 stainless steel has good formability and processability, and is suitable for cold and hot processing.
Wide range of applications: 304 stainless steel is widely used in food processing equipment, chemical equipment, architectural decoration, household products and other fields.
In the naming of stainless steel, " L "stands for "Low Carbon". The " L " in 304L stainless steel indicates that its carbon content is lower than that of ordinary 304 stainless steel. Specifically, the carbon content of 304 stainless steel is usually below 0.08%, while the carbon content of 304L stainless steel is below 0.03%.
Better welding performance: Due to its low carbon content, 304L stainless steel is less likely to form carbide precipitation during the welding process, thereby reducing the risk of welding cracks and intergranular corrosion.
Excellent corrosion resistance: 304L stainless steel has better corrosion resistance under welding and high temperature conditions.
Suitable for applications requiring welding: 304L stainless steel is particularly suitable for storage tanks, pipes and other structures that require frequent welding.
Chemical properties:
|
Grade |
C |
Mn |
Si |
P |
S |
Cr |
Mo |
Ni |
N |
|
304 |
≤0.08 |
≤2.0 |
≤0.75 |
≤0.045 |
≤0.030 |
18.0-20.0 |
- |
8.0-10.5 |
≤0.10 |
|
304L |
≤0.030 |
≤2.0 |
≤0.75 |
≤0.045 |
≤0.030 |
18.0- |
- |
8.0- |
≤0.10 |
The main difference between 304L stainless steel and 304 stainless steel is the carbon content. 304L stainless steel has a lower carbon content (maximum 0.03%), which helps prevent the formation of carbide precipitation during the welding process, thereby reducing the risk of intergranular corrosion.
Mechanical properties:
|
Grade |
Tensile Strength (MPa) min |
Yield Strength 0.2% Proof (MPa) min |
Elongation (% in 50mm) min |
Hardness |
|
|
Rockwell B (HR B) max |
Brinell (HB) max |
||||
|
304 |
515 |
205 |
40 |
92 |
201 |
|
304L |
485 |
170 |
40 |
92 |
201 |
The mechanical properties of 304L stainless steel plate are similar to 304 stainless steel, but due to the lower carbon content, its tensile strength and yield strength are slightly lower.
304 stainless steel is widely used in the following fields:
Food processing equipment: such as brewing equipment, dairy equipment, food processing and packaging equipment.
Chemical equipment: such as storage tanks, pipelines and reactors.
Architecture and decoration: such as building facades, decorative finishes, handrails and railings.
Household products: such as kitchen utensils, sinks and tableware.
304L stainless steel is mainly suitable for applications requiring welding, including:
Storage tanks and pressure vessels: such as chemical storage tanks, food storage tanks and pressure vessels.
Pipeline systems: such as oil and gas pipelines, chemical pipelines.
Heat exchangers: such as heat exchangers, condensers and boiler tubes.
Marine environment: such as ships, offshore platforms and marine equipment.
General corrosion:
The corrosion resistance of 304 and 304L stainless steel is basically the same in most ordinary environments, including atmospheric environments, fresh water environments, and many chemical environments. But under high temperature or welding conditions, 304L stainless steel has better corrosion resistance.
Intergranular corrosion:
Intergranular corrosion refers to the localized corrosion of stainless steel caused by the precipitation of carbides during the high temperature or welding process, which reduces the chromium content at the grain boundaries. Due to its low carbon content, 304L stainless steel is less likely to form carbide precipitation after welding, so its resistance to intergranular corrosion is better than that of 304 stainless steel.
Pitting and crevice corrosion
Pitting and crevice corrosion often occur in chlorine-containing environments. 304 and 304L stainless steels have similar pitting and crevice corrosion resistance in environments with low to moderate chloride ion concentrations. However, in high chloride ion concentration environments, it may be necessary to use a higher grade of stainless steel (such as 316 stainless steel) to obtain better corrosion resistance.
When choosing between 304 and 304L stainless steel, users need to make decisions based on specific applications and environmental conditions. Here are some selection guidelines:
Application environment: In ordinary atmospheric and fresh water environments, 304 stainless steel is usually a good choice. If the application involves high temperatures or welding, 304L stainless steel is more suitable.
Mechanical performance requirements: If higher strength and toughness are required, 304 stainless steel is ideal. If better welding performance and resistance to intergranular corrosion are required, 304L stainless steel is more suitable.
Cost considerations: Due to different production processes, the cost of 304L stainless steel is usually slightly higher than that of 304 stainless steel. When on a budget, 304 stainless steel may be more cost effective.
If you want to know more about stainless steel plate/pipe, please contact us!
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