Introduction
SUS316L is the low-carbon variant of SUS316 stainless steel, where "L" stands for Low Carbon (C ≤ 0.03%). By reducing carbon content below that of standard SUS316, carbide precipitation at grain boundaries during welding is minimized — effectively eliminating sensitization and preserving corrosion resistance in the heat-affected zone (HAZ).
Like SUS316, SUS316L contains 2.0–3.0% molybdenum (Mo) and elevated nickel, giving it outstanding resistance to chloride-induced pitting and crevice corrosion. It is widely used in chemical processing, marine facilities, medical devices, and food processing equipment where both high corrosion resistance and weldability are required.
SUS316L is also notable for its maximum carbon content of 0.03%, which allows it to be used in welded assemblies without post-weld annealing — a significant practical advantage over standard SUS316.
Standard Equivalents
Chinese National Standards (GB)
- GB/T 1220: 316L → 00Cr17Ni14Mo2 (also: 022Cr17Ni12Mo2, S31603)
- GB/T 20878: 316L → 00Cr17Ni14Mo2 (also: 022Cr17Ni12Mo2, S31603)
ASTM Standards
- ASTM A240: Plate, sheet, and strip for pressure vessels — 316L / S31603
- ASTM A276: Stainless steel bar and shapes — 316L / S31603
- ASTM A312: Seamless and welded austenitic stainless steel pipes — TP316L / S31603
JIS Standards
- JIS G4303: Stainless steel bars — SUS316L
- JIS G4304: Hot-rolled stainless steel plate and sheet — SUS316L
- JIS G4305: Cold-rolled stainless steel plate and sheet — SUS316L
This page uses JIS G4303 as the primary reference.
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SUS316L Chemical Composition
Reference standard: JIS G4303
| Grade | C (%) | Mn (%) | Si (%) | P (%) | S (%) | Ni (%) | Mo (%) | Cr (%) |
|---|---|---|---|---|---|---|---|---|
| SUS316L | ≤ 0.03 | ≤ 2.00 | ≤ 1.00 | ≤ 0.045 | ≤ 0.03 | 10.00–14.00 | 2.00–3.00 | 16.00–18.00 |
Key difference from SUS316: Carbon is reduced from ≤ 0.08% to ≤ 0.03%. All other elements are identical. This single change delivers significantly improved weldability and post-weld corrosion resistance.
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) |
|---|---|---|---|---|---|---|---|
| SUS316L | ≥ 480 | ≥ 175 | ≥ 40 | ≥ 60 | ≤ 187 HB / ≤ 90 HRB / ≤ 200 HV | 7.98 | 1375–1450 |
Note: Compared to SUS316 (σb ≥ 520 MPa, σ0.2 ≥ 205 MPa), SUS316L has slightly lower tensile and yield strength as a result of reduced carbon. This trade-off is well-accepted in applications where weldability and corrosion resistance are the primary requirements.
Other Physical Properties
| Property | Value |
|---|---|
| Melting Point | 1375–1450 °C |
| Solution Annealing Temperature | 1010–1150 °C |
| Microstructure | Austenitic |
| Electrical Resistivity | 73.0 μΩ·cm |
| Specific Heat Capacity | 0.45 J/(g·K) |
SUS316L vs SUS316: When to Choose Which
| Criteria | SUS316 | SUS316L |
|---|---|---|
| Carbon content | ≤ 0.08% | ≤ 0.03% |
| Tensile strength | ≥ 520 MPa | ≥ 480 MPa |
| Yield strength | ≥ 205 MPa | ≥ 175 MPa |
| Weldability | Good | Excellent (no post-weld anneal required) |
| Sensitization risk | Present at high temps | Minimal |
| Post-weld heat treatment | Recommended | Not required |
| Best for | High-strength structural parts | Welded assemblies, pressure vessels, medical & food equipment |
Applications of SUS316L Stainless Steel
SUS316L's combination of low carbon, molybdenum, and high nickel makes it indispensable across demanding industries:
- Pulp & Paper Industry — heat exchangers, bleaching equipment, and process piping
- Chemical & Dye Processing — production equipment for oxalic acid, fertilizers, and dye baths
- Marine & Coastal — seawater-exposed equipment, offshore structures, coastal building exteriors, ropes, and CD bars. SUS316L is the preferred grade for marine environments due to its superior chloride resistance.
- Food & Beverage — processing and storage equipment for salt-containing products
- Medical Devices — surgical instruments, implants, and pharmaceutical processing equipment
- Photography & Film Processing — film developing equipment
- Fasteners — bolts, nuts, and screws in corrosive or welded assemblies (note: for high-volume CNC turning of fasteners, SUS303 is preferred due to its superior machinability)
- Sulfuric acid environments — SUS316L performs well when H₂SO₄ concentration is below 15% or above 85% at elevated temperatures
Browse our marine-grade A4 stainless steel fasteners: Marine Carriage Bolts (DIN 603), Marine Weld Nuts (DIN 929), Marine Nylon Locking Nuts (DIN 982), and Marine Eye Bolts (DIN 444).
Fabrication Characteristics
Weldability
SUS316L's primary advantage is its excellent weldability. All standard welding methods are applicable. Recommended filler materials include 316Cb, 316L, or 309Cb stainless steel rods or electrodes depending on the application. Crucially, post-weld annealing is not required when using SUS316L — unlike standard SUS316, which benefits from post-weld heat treatment to restore corrosion resistance.
Formability
SUS316L has good cold workability and can be formed by stamping, deep drawing, bending, and roll forming, suitable for manufacturing complex-shaped components.
Machinability (Turning)
SUS316L is not well-suited for high-speed turning. Chips tend to form long, stringy, spring-like strands that do not break away cleanly, requiring manual chip clearing to maintain continuous machining. For precision CNC turning applications, SUS303 free-machining stainless steel is strongly recommended instead.
Heat Treatment
Solution annealing is performed at 1010–1150°C followed by rapid quenching. SUS316L cannot be hardened by heat treatment. Annealing can be used to relieve work hardening after cold forming.
Surface Treatment
SUS316L accepts a wide range of surface finishes including polishing, pickling, passivation, and electroplating to enhance appearance and corrosion resistance.
Standards reference: JIS G4303 | JIS G4304 | JIS G4305 | ASTM A240 | ASTM A276 | ASTM A312 | GB/T 1220 | GB/T 20878
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