If you need a stainless steel that resists corrosion in high-heat or chemical-rich environments—like in food processing or pharmaceuticals—JIS SUS304L stainless steel is a top choice. It’s a low-carbon version of the popular SUS304, with extra protection against intergranular corrosion. This guide covers everything you need to know to use it effectively for your projects.
What are the key properties of SUS304L?
JIS SUS304L stands out for its balanced material properties, thanks to its carefully crafted alloy makeup. The key difference from SUS304 is lower carbon content, which prevents intergranular corrosion.
Chemical composition
The precise mix of elements gives SUS304L its performance, with one critical difference: lower carbon.
| Element | Content Range (%) | Role in Performance |
|---|---|---|
| Chromium (Cr) | 18.0 – 20.0 | Forms protective oxide layer, boosts corrosion resistance |
| Nickel (Ni) | 8.0 – 12.0 | Stabilizes austenitic structure, improves ductility |
| Carbon (C) | ≤ 0.03 | Prevents intergranular corrosion (the “L” stands for low carbon) |
| Manganese (Mn) | ≤ 2.0 | Enhances workability during manufacturing |
| Silicon (Si) | ≤ 1.0 | Reduces oxidation at high temperatures |
Mechanical and physical properties
SUS304L is strong enough for industrial use, yet flexible enough for forming.
| Property | Typical Value | Practical Benefit |
|---|---|---|
| Tensile strength | 485 MPa | Handles pressure for pipes and tanks |
| Yield strength | 170 MPa | Resists bending for structural parts |
| Elongation | ≥ 40% | Bends without cracking for curved shapes |
| Hardness | ≤ 210 HB | Soft enough for machining, durable against scratches |
| Density | 7.9 g/cm³ | Similar to SUS304, easy to replace in existing designs |
| Thermal conductivity | 16.3 W/(m·K) at 100°C | Transfers heat evenly for heat exchangers |
| Magnetic properties | Non-magnetic | Won’t stick to magnets |
A pharmaceutical equipment maker in Japan uses SUS304L for mixing tanks. Its high elongation lets them form tanks into custom shapes, while low carbon ensures no corrosion from harsh cleaning chemicals.
Where is SUS304L used?
Thanks to its corrosion resistance and low carbon content, SUS304L is used in industries where purity and durability matter most.
Food processing equipment
Mixers, conveyor belts, and storage tanks meet food safety standards like JIS Z 2801 and resist acids from fruits or dairy. A bakery in France uses it for dough mixers—no rust from wet dough, even after daily use.
Pharmaceutical equipment
Drug manufacturing tanks and sterile conveyors. Low carbon prevents metal particles from leaching into drugs. A pharmaceutical plant in Germany uses SUS304L for pill-making machines—passes strict purity tests.
Chemical processing plants
Pipes and reactors handling mild chemicals like ethanol. Resists intergranular corrosion when heated. A chemical firm in China uses it for solvent pipes—no leaks or corrosion for 5 years.
Medical devices
Surgical tools and exam tables are easy to sterilize and non-toxic. A hospital in South Korea uses SUS304L for scalpels—stays sharp and rust-free after autoclaving.
Sanitary fittings
Faucets and showerheads in hospitals or labs resist bacteria buildup and harsh cleaners. A lab facility in Singapore uses it for sink faucets—no mineral deposits or corrosion.
Electrical appliances
Oven interiors and refrigerator shelves handle heat and moisture without rust. A major appliance brand uses it for oven liners—lasts over 10 years with regular use.
How is SUS304L manufactured?
SUS304L is easy to work with, making it popular for manufacturers.
Forming processes
- Hot rolling: Heated to 1,100–1,200°C and rolled into thick plates or bars. Used for large parts like tank shells.
- Cold rolling: Done at room temperature to make thin sheets for appliance panels. Improves surface smoothness.
- Drawing: Pulled through dies to make wires or small tubes for medical needles or electrical wires.
Heat treatment and finishing
- Annealing: Heated to 1,010–1,120°C and cooled slowly. Softens steel after cold working for easier shaping without cracking.
- Pickling: Treated with nitric acid to remove scale from rolling or welding. Improves corrosion resistance.
- Machining: Drilled, cut, or milled with high-speed steel tools. Use coolant to avoid overheating.
What corrosion resistance does SUS304L offer?
The biggest advantage of SUS304L is its superior corrosion resistance, especially against intergranular corrosion.
Key corrosion-resistant traits
- Intergranular corrosion resistance: Low carbon below 0.03% prevents carbide precipitation, a cause of cracking in high heat. A chemical plant tested SUS304 versus SUS304L at 600°C—SUS304 cracked in 3 months, while SUS304L stayed intact.
- Pitting resistance: Resists small holes in mild chlorides like tap water. Tests show it withstands 150 ppm chloride levels without pitting.
- Crevice corrosion: Performs well in tight spaces like bolted joints if cleaned regularly.
- Stress corrosion cracking: Resists cracking under stress and corrosion in pressure pipes. A refinery uses it for fuel lines—no issues after 4 years.
Surface treatment: Passivation with acid thickens the oxide layer. A food factory passivates SUS304L tanks—extends their life by 3 times.
Note: It’s not ideal for full seawater submersion. Use SUS316L instead. Works for coastal parts with regular maintenance.
How should SUS304L be welded?
SUS304L has good weldability, but follow best practices to avoid issues.
Welding guidelines
| Parameter | Recommendation |
|---|---|
| Processes | TIG for thin parts like pipes; MIG for thicker sections |
| Filler rods | Low-carbon AWS ER308L to match SUS304L’s low carbon |
| Shielding gas | Argon for TIG; argon-CO₂ mixes for MIG |
| Post-weld heat treatment | Not always needed; annealing at 1,010–1,120°C removes stress |
| Inspection | X-ray or ultrasonic testing for critical parts |
A pipe welder once used ER308 filler with high carbon. The weld cracked in 6 months. Always use ER308L to prevent intergranular corrosion.
What standards govern SUS304L?
To ensure quality, SUS304L follows strict global standards.
| Standard | Description |
|---|---|
| JIS G4303 | Japanese standard for cold-rolled stainless steel sheets |
| ASTM A240 | U.S. standard; Type 304L is interchangeable with SUS304L |
| EN 10088 | European standard; X2CrNi18-10 is the equivalent grade |
| ISO 15510 | International standard covering chemical composition |
Material certification: Ask for a mill certificate or Material Test Certificate to verify compliance. A pharmaceutical client requires MTCs for all SUS304L parts—ensures purity for drug manufacturing.
How does SUS304L compare to other materials?
Understanding how SUS304L stacks up helps with material selection.
| Material | Advantage vs. SUS304L | Disadvantage vs. SUS304L | Best For |
|---|---|---|---|
| SUS304 | Lower cost (~5% cheaper) | Prone to intergranular corrosion | Non-heated applications like furniture |
| SUS316L | Better seawater corrosion | More expensive (~30% higher) | Marine parts, coastal architecture |
| Carbon steel | Much cheaper (~50% lower) | No corrosion resistance | Indoor structural parts like beams |
| Duplex stainless | Higher strength | Less ductile, harder to form | High-pressure pipes |
| Titanium | Extreme corrosion resistance | Very expensive (~5x cost) | Aerospace, deep-sea equipment |
| Aluminum | Lighter at 2.7 g/cm³ | Less strong at 276 MPa tensile | Lightweight parts like bike frames |
Key takeaway: For most high-heat or chemical applications like food processing and pharmaceuticals, SUS304L offers the best balance of cost and corrosion resistance.
Conclusion
JIS SUS304L stainless steel delivers excellent corrosion resistance, especially against intergranular corrosion, for high-heat and chemical-rich environments. Its low carbon content below 0.03% prevents carbide precipitation during welding and high-temperature service, while its austenitic structure provides good formability. For food processing equipment, pharmaceutical tanks, and medical devices where purity and durability matter, it offers reliable performance at a reasonable cost.
FAQ
What’s the difference between SUS304 and SUS304L?
The main difference is carbon content. SUS304 has ≤0.08% carbon, while SUS304L has ≤0.03%. This makes SUS304L resistant to intergranular corrosion—critical for high-heat applications like ovens or chemical reactors.
Can SUS304L be used in seawater?
It’s not ideal for full submersion—SUS316L is better. But it works for coastal parts like patio furniture if cleaned monthly to remove salt spray. This prevents pitting.
Is SUS304L easy to weld?
Yes. It has good weldability with TIG or MIG processes. Use low-carbon filler rods like AWS ER308L and protect the weld with argon gas. For critical parts, post-weld annealing removes stress.
Does SUS304L require passivation?
Passivation is recommended after welding or machining. Treating with nitric acid thickens the protective chromium oxide layer, improving corrosion resistance. Food and pharmaceutical applications typically require passivation.
Is SUS304L magnetic?
No. SUS304L has an austenitic microstructure, which makes it non-magnetic. This is a quick way to tell it apart from magnetic stainless steels like SUS430.
Discuss Your Projects with Yigu Rapid Prototyping
At Yigu Rapid Prototyping, we supply JIS SUS304L stainless steel for food processing, pharmaceutical, and chemical applications. Our material meets JIS, ASTM, and EN standards with full mill test certificates. We offer custom forming, welding, and passivation services to match your requirements. Contact us to discuss your next corrosion-resistant project.