Type 304L stainless steel is low carbon version of 304 alloy, it is also austenitic steel, the “L” stands for LOW carbon, the carbon content is max 0.035%, 304L exhibits excellent corrosion resistance thanks to the lower carbon content, and has good fabrication and outstanding formability characteristics.
304L Stainless Steel Chemical Composition
The chemical composition of 304L stainless steel consists of 18-20% chromium and 8-12% nickel content, combined with a maximum of 0.03% carbon, 2% manganese, 1% silicon, 0.11% nitrogen, 0.045% phosphorus, and 0.03% sulfur, compared to 304 stainless steel, these two alloys are very similar, but there is one key difference in carbon content, the maximum carbon content in 304 0.08%.
The typical chemical composition for this grade is given in the table below, together with composition limits given for the product according to different standards. The required standard will be fully met as specified on the order.
The chemical composition is given as % by mass.
| Standard | Grade | C | Mn | P | S | Si | Cr | Ni | N |
|---|---|---|---|---|---|---|---|---|---|
| ASTM A240 | 304L | ≤0.030 | ≤2.00 | 0.045 | 0.030 | 1.0 | 18.0-20.0 | 8.0-12.0 | ≤0.10 |
| ASTM A312 | TP304L | ≤0.035 | ≤2.00 | 0.045 | 0.030 | 1.0 | 18.0-20.0 | 8.0-12.0 | ≤0.10 |
| EN 10028-7 | 1.4307 | ≤0.030 | ≤2.00 | 0.045 | 0.030 | 1.0 | 17.5-19.5 | 8.0-10.5 | ≤0.10 |
| EN 10088-2 | 1.4307 | ≤0.030 | ≤2.0 | 0.045 | 0.030 | 1.0 | 17.5-19.5 | 8.0-10.5 | ≤0.10 |
| EN 10088-3 | 1.4307 | ≤0.030 | ≤2.00 | 0.045 | 0.030 | 1.0 | 17.5-19.5 | 8.0-10.5 | ≤0.10 |
| EN 10088-4 | 1.4307 | ≤0.030 | ≤2.0 | 0.045 | 0.030 | 1.0 | 17.5-19.5 | 8.0-10.5 | ≤0.10 |
304L Stainless Steel Mechanical Properties
304L grade has slightly lower mechanical properties than the standard 304 grade, this means that 304L stainless steel is weaker than the standard 304 alloys, but it is still widely used in many applications, It can be used at low temperatures down to -196 °C/384.8 °F even in welded structures. Moderate strengths can be reached at elevated temperatures (~550 °C/1022 °F). Temperatures for excessive scaling are close to 850 °C/1562 °F.
| Standard | Grade | Yield Strength | Tensile Strength | Elongation | Hardness | Hardness |
|---|---|---|---|---|---|---|
| MPa | MPa | %, Min | Rockwell, HRB | HB, Maz | ||
| ASTM A240 | 304L | ≥ 170 | ≥ 485 | 35 | 92 | 201 |
| EN 10028-7 | 1.4307 | ≥ 220 | 520-700 | 35 | 215 | |
| EN 10088-2 | 1.4307 | ≥ 220 | 520-700 | 35 | 215 | |
| EN 10088-4 | 1.4307 | ≥ 220 | 520-700 | 35 | 215 |
304L Stainless Steel Equivalent Grades
| AISI | UNS | DIN | EN | JIS | GB |
|---|---|---|---|---|---|
| 304L | S30403 | 1.4307 | X5CrNi18-10 | SUS304L | 022Cr19Ni10 |
304L Stainless Steel Physical Properties
Physical properties according to EN 10088 are given in the table below.
| Density | Melting Point | Modulus Of Elasticity | Thermal Exp. At 100 °C | Thermal Conductivity | Thermal Capacity | Electrical Resistance |
|---|---|---|---|---|---|---|
| Kg/Dm3 | （℃） | GPa | 10-6/°C | W/M°C | J/Kg°C | ΜΩm |
| 7.9 | 1398~1427 | 200 | 16.0 | 15 | 500 | 0.73 |
Benefits Of 304L Stainless Steel
In practice, both 304 and 304L can be used for many of the same applications, dual certified stainless steel is available, and 304L/4307 is often double-certified as EN 1.4301/1.4307, ASTM Type 304/304L.
- Low carbon content eliminates carbon precipitation in the welding process
- Can be used in severe corrosive environments
- Weld annealing is only required in high-stress applications
- Very similar to Type 304
Corrosion Resistance
304L stainless steel has excellent corrosion resistance, It can withstand many organic and sufficiently diluted mineral acids depending on the temperature of the solution. Due to its low carbon content, the risk of sensitization for intergranular corrosion after welding is strongly reduced when compared to other austenitic CrNi standard grades with normal carbon content.
304L is preferred for use in environments sufficiently corrosive to cause intergranular corrosion of welds and heat-affected zones on susceptible alloys.
In aqueous solutions containing halogenides, e.g. chlorides or bromides, pitting and crevice corrosion may occur depending on halogenide concentration, temperature, pH value, concentration of oxidizing compounds, and crevice geometry, if applicable.
304L steel has lower carbon content, the risks of chrome carbide precipitation are much minimized, and it may show a lower corrosion rate than the higher carbon Alloy 304.
Welding
304L/4307 has excellent weldability and is suitable for the full range of conventional welding methods (like MMA, MIG, MAG, TIG, SAW, LBW, or RSW), except gas welding.
Core 304L/4307 has about 50% higher thermal expansion and lower heat conductivity compared to carbon steels. This means that larger deformation and higher shrinkage stresses may result from welding.
Post-weld heat treatment is generally not required. In special cases where there is high risk of stress corrosion cracking or fatigue, stress relief treatment may be considered.
To fully restore the corrosion resistance of the weld seam, the weld discoloration should be removed by pickling and passivation.
304L Stainless Steel Forms
Stainless Steel Standards
- ASTM A240/ASME SB240, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
- ASTM A480, Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip
- EN 10088-2, Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion-resisting steels for general purposes
- EN 10088-3, Stainless steels. Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion-resisting steels for general purposes
- EN 10088-4, Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion-resisting steels for construction purposes
- EN 10088-5, Stainless steels. Technical delivery conditions for bars, rods, wire, sections and bright products of corrosion-resisting steels for construction purposes
- ASTM A249, Standard Specification for Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes
- ASTM A213, Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
- ASTM A312, Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
- ASTM A276, Standard Specification for Stainless Steel Bars and Shape
304L stainless steel vs 316L, What is the difference?
304L and 316L stainless steels are austenitic steel grades with low carbon content (max 0.03%), but 304L stainless steel contains 18-20% chromium and 8-11% nickel while 316 stainless steel contains 16-18% chromium, 10-12% nickel, and 2-3% molybdenum, the main difference between 304L and 316L stainless steel is that 316L stainless steel has 2-3% of molybdenum content, which makes 316L better corrosion resistant than 304L, and 316L is suitable for application of chloride environment, but 316L is more expensive.
304L stainless steel vs 304, What is the difference?
304 and 304L are austenitic stainless steel grades, the difference between 304 stainless steel and 304L is in carbon element, 304 has a max of 0.07% carbon but 304L has a max of 0.03%, this difference in composition makes a difference in properties, 304L has a lower tensile strength of 485 Mpa compared to 304 (515 Mpa). 304L is easier to weld, but its primary advantage is lesser carbide precipitation, which also results in improved corrosion resistance. In practice, both 304 and 304L can be used for many of the same applications and can be dual-certified stainless steel.