The main difference between 304 and 304L stainless steel lies in their carbon content: 304 stainless steel has a maximum carbon content of 0.08%, while 304L (low-carbon) stainless steel has a maximum carbon content of 0.03%. Therefore, 304L is more suitable for welding applications because it prevents carbide precipitation, which can lead to corrosion in welded 304 stainless steel. Although 304 stainless steel is slightly stronger, 304L stainless steel offers better resistance to intergranular corrosion after welding, making it ideal for thick-section components and corrosive environments (such as chemical processing or marine environments), and typically eliminates the need for post-weld annealing.
What does the "L" in 304L stainless steel stand for?
The letter L after the grade number, such as 304L, indicates that the carbon content is limited to below 0.03% (the normal maximum carbon content is 0.08%, and some grades can have a carbon content as high as 0.15%).
What is 304 stainless steel?
304 stainless steel, also known as A2 or 18/8 stainless steel, contains 18% chromium and 8% nickel, offering good corrosion resistance, formability, and durability. It cannot be hardened by heat treatment and is typically used in the annealed state. It is weldable and machinable, and commonly used in sinks, food storage tanks, surgical instruments, and exhaust systems.
What is 304L stainless steel?
304L stainless steel is a strong, silver-gray alloy composed of 70% iron, 18% chromium, and 8% nickel. The "L" stands for "low carbon," with a carbon content of 0.03%, lower than 304 stainless steel. This prevents carbide precipitation during welding and improves corrosion resistance. It performs well in corrosive environments without the need for annealing. This material is primarily used in industries such as chemical processing, beverage processing, food manufacturing, and construction.
Chemical Composition of 304 vs 304L (by Weight%)
| Element | 304 Stainless Steel | 304L Stainless Steel |
| Carbon (C) | ≤ 0.08% | ≤ 0.03% |
| Chromium (Cr) | 18.0-20.0% | 18.0-20.0% |
| Nickel (Ni) | 8.0-10.5% | 8.0-12.0% |
| Manganese (Mn) | ≤ 2.00% | ≤ 2.00% |
| Silicon (Si) | ≤ 0.75% | ≤ 0.75% |
| Phosphorus (P) | ≤ 0.045% | ≤ 0.045% |
| Sulfur (S) | ≤ 0.030% | ≤ 0.030% |
| Nitrogen (N) | ≤ 0.10% | ≤ 0.10% |
| Molybdenum (Mo) | No | No |
Physical Property of 304 vs 304L
| Property | 304 Stainless Steel | 304L Stainless Steel |
| Density | 8.0 g/cm³ | 8.0 g/cm³ |
| Melting Point | 1400°C – 1450°C | 1400°C – 1450°C |
| Thermal Conductivity | 16.2 W/m·K at 100°C | 16.2 W/m·K at 100°C |
| Modulus of Elasticity | 193 GPa | 193 GPa |
| Tensile Strength | ~515 MPa | ~485 MPa |
Mechanical Properties of 304 vs 304L
| Property | 304 Stainless Steel | 304L Stainless Steel |
| Tensile Strength | 515 MPa | 485 MPa |
| Yield Strength | 205 MPa | 170 MPa |
| Elongation at Break | 40% | 40% |
| Hardness (Rockwell B) | 82 | 82 |
| Impact Toughness | High | High |
Equivalent Grades of 304 and 304L
| Country/Standard | Specification | Grade (304) | Grade (304L) |
| United States | ASTM A240, ASTM A312 | 304 | 304L |
| China | GB/T 1220, GB/T 14975 | 0Cr18Ni9 | 00Cr19Ni10 |
| Japan | JIS G4304, JIS G4305 | SUS304 | SUS304L |
| International | ISO 15510 | X5CrNi18-10 | X2CrNi19-11 |
| Europe | EN 10088-2 | 1.4301 | 1.4307 |
Applications of 304 and 304L Stainless Steel
Although 304 and 304L stainless steels have similar chemical and physical properties, their differing carbon content leads to differences in their application areas. These differences determine the most suitable applications for each grade.
Applications of 304 Stainless Steel
Structural components: Used in building frames, bridges, and load-bearing structures.
Automotive parts: Commonly used in exhaust systems, engine components, and decorative trim.
Industrial equipment: Suitable for tanks, pipes, and machinery exposed to various chemicals.
Consumer goods: Used in kitchen sinks, cookware, and household appliances.
Medical devices: Used in surgical instruments, dental tools, and hospital equipment.
Food processing equipment: Used in food storage, handling, and preparation equipment, such as containers, utensils, and conveyor systems.
Applications of 304L Stainless Steel
Welded structures: Preferred for welded pipes, tanks, and heat exchangers.
Chemical processing: Used in equipment for handling corrosive chemicals, such as reactors and mixing tanks.
Marine environments: Suitable for shipbuilding, offshore platforms, and underwater pipelines.
Pharmaceutical equipment: Applied in drug manufacturing equipment where high purity is required.
Food processing: Ideal for handling acidic foods and beverages, such as fermentation tanks and food storage units.
Gnee Steel also supplies custom stainless stee 304 products in various sizes and specifications. Please send us your drawings for a quote!