Introduction
SUS304L is the low-carbon variant of the 304 stainless steel family, where "L" stands for Low Carbon. Compared to standard SUS304, the carbon content of SUS304L is reduced to 0.03% maximum, which significantly improves resistance to sensitization and intergranular corrosion — particularly in welded assemblies.
SUS304L is an austenitic stainless steel governed by multiple international standards. The key equivalents are:
Chinese National Standards (GB)
- GB/T 1220: 304L corresponds to 00Cr19Ni10 (also designated 022Cr19Ni10 or S30403)
- GB/T 20878: 304L corresponds to 00Cr19Ni10 (also designated 022Cr19Ni10 or S30403)
ASTM Standards
- ASTM A240: Stainless steel plate, sheet, and strip for pressure vessels and general use — designates 304L / S30403
- ASTM A276: Stainless steel bar and shapes — designates 304L / S30403
- ASTM A312: Seamless and welded austenitic stainless steel pipes — designates TP304L / S30403
JIS Standards
- JIS G4303: Stainless steel bars — designates SUS304L
- JIS G4304: Hot-rolled stainless steel plate and sheet — designates SUS304L
- JIS G4305: Cold-rolled stainless steel plate and sheet — designates SUS304L
This page uses JIS G4303 as the primary reference.
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SUS304L Chemical Composition
Reference standard: JIS G4303
| Grade | C (%) | Mn (%) | Si (%) | P (%) | S (%) | Ni (%) | Mo (%) | Cr (%) |
|---|---|---|---|---|---|---|---|---|
| SUS304L | ≤ 0.03 | ≤ 2.00 | ≤ 1.00 | ≤ 0.045 | ≤ 0.03 | 9.00–13.00 | — | 18.00–20.00 |
Key difference from SUS304: Carbon is reduced from ≤ 0.08% to ≤ 0.03%, and nickel range is slightly wider (9.00–13.00% vs. 8.00–10.5%). All other elements remain the same.
Physical and Mechanical Properties
Mechanical Properties (JIS G4303)
| Grade | Tensile Strength σb (MPa) | Yield Strength σ0.2 (MPa) | Elongation δ5 (%) | Reduction of Area ψ (%) | Hardness | Density (g/cm³) | Melting Point (°C) |
|---|---|---|---|---|---|---|---|
| SUS304L | ≥ 480 | ≥ 175 | ≥ 40 | ≥ 60 | ≤ 187 HB / ≤ 90 HRB / ≤ 200 HV | 7.93 | 1398–1420 |
Note: Compared to SUS304 (σb ≥ 520 MPa, σ0.2 ≥ 205 MPa), SUS304L has slightly lower tensile and yield strength due to its reduced carbon content. This trade-off is acceptable in most applications where weldability and corrosion resistance take priority over maximum strength.
Other Physical Properties
| Property | Value |
|---|---|
| Melting Point | 1398–1420 °C |
| Specific Heat Capacity (0–100°C) | 0.50 kJ/(kg·K) |
| Thermal Conductivity at 100°C | 16.3 W/(m·K) |
| Thermal Conductivity at 500°C | 21.5 W/(m·K) |
| Thermal Expansion (0–100°C) | 17.2 × 10⁻⁶ /K |
| Thermal Expansion (0–500°C) | 18.4 × 10⁻⁶ /K |
| Electrical Resistivity (20°C) | 0.73 × 10⁻⁶ Ω·m |
| Elastic Modulus (20°C) | 193 kN/mm² |
Applications of SUS304L Stainless Steel
The low carbon content of SUS304L makes it the preferred choice wherever welding is involved and post-weld heat treatment is impractical:
- Chemical & Petrochemical Industry — storage tanks, pipelines, reactors, and pressure vessels where intergranular corrosion resistance is critical
- Food Processing — production equipment, storage containers, and conveyor systems requiring hygienic surfaces and easy cleaning
- Pharmaceutical Industry — process equipment where low ferrite formation prevents product contamination
- Architecture & Decoration — building facades, handrails, staircases, and decorative panels
- Marine Applications — ship components and offshore platform fittings in corrosive seawater environments
For marine-grade stainless steel fasteners, browse our Marine Stainless Steel Carriage Bolts (DIN 603), Marine Castle Nuts (DIN 935), and Marine Eye Bolts (DIN 444).
Fabrication Characteristics
Weldability
SUS304L's primary advantage is its excellent weldability. The reduced carbon content minimizes carbide precipitation at grain boundaries during welding, effectively preventing sensitization and intergranular corrosion in the heat-affected zone (HAZ). Common welding methods include TIG (argon arc) welding and laser welding. Post-weld heat treatment is generally not required.
Formability
SUS304L has good cold workability and can be formed by stamping, deep drawing, bending, and roll forming. It is well-suited for manufacturing complex-shaped components.
Heat Treatment
SUS304L does not require heat treatment to improve mechanical properties. However, annealing can be applied to relieve work hardening and restore ductility after cold forming operations.
Surface Treatment
The surface of SUS304L is easy to clean and can be finished by polishing, pickling, passivation, or electroplating to enhance appearance and corrosion resistance.
SUS304L vs SUS304: When to Choose Which
| Criteria | SUS304 | SUS304L |
|---|---|---|
| Carbon content | ≤ 0.08% | ≤ 0.03% |
| Tensile strength | ≥ 520 MPa | ≥ 480 MPa |
| Yield strength | ≥ 205 MPa | ≥ 175 MPa |
| Weldability | Good | Excellent (no sensitization risk) |
| Intergranular corrosion resistance | Standard | Superior (especially post-weld) |
| Typical use | General purpose, cold-headed fasteners | Welded assemblies, pressure vessels, food & pharma equipment |
For a full overview of the standard 304 grade, see our article on SUS304 Stainless Steel Chemical Composition and Standards.
Standards reference: JIS G4303 | JIS G4304 | JIS G4305 | ASTM A240 | ASTM A276 | ASTM A312 | GB/T 1220 | GB/T 20878
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