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 a common issue: intergranular corrosion. This guide covers everything you need to know to use it effectively for your projects.
1. Material Properties of JIS SUS304L Stainless Steel
JIS SUS304L stainless steel stands out for its balanced material properties, thanks to its carefully crafted alloy makeup. Let’s start with its core characteristics:
Alloy Composition
The key to its performance is a precise mix of elements, with one critical difference from SUS304: lower carbon. Here’s the breakdown:
| Element | Content Range | Role in Performance |
|---|---|---|
| Chromium | 18.0% – 20.0% | Forms a protective oxide layer (boosts corrosion resistance) |
| Nickel | 8.0% – 12.0% | Stabilizes the austenitic structure (improves ductility) |
| Carbon | ≤0.03% | Prevents intergranular corrosion (the “L” in SUS304L stands for “low carbon”) |
| Manganese | ≤2.0% | Enhances workability during manufacturing |
| Silicon | ≤1.0% | Reduces oxidation at high temperatures |
Mechanical & Physical Properties
It’s strong enough for industrial use, yet flexible enough for forming. Here’s how it performs:
| Property | Typical Value | Practical Benefit |
|---|---|---|
| Mechanical Strength (Tensile) | 485 MPa | Handles pressure (good for pipes or tanks) |
| Yield Strength | 170 MPa | Resists bending (ideal for structural parts like brackets) |
| Elongation | ≥40% | Bends without cracking (great for curved trim or containers) |
| Hardness | ≤210 HB (Brinell) | Soft enough for machining, but 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 (suitable for heat exchangers) |
| Electrical Conductivity | 1.4 x 10⁶ S/m | Lower than copper (good for parts where electrical resistance is needed) |
| Magnetic Properties | Non-magnetic | Won’t stick to magnets (unlike ferritic or martensitic steels) |
A pharmaceutical equipment maker in Japan uses SUS304L for mixing tanks. Its high elongation lets them form the tanks into custom shapes, while the low carbon ensures no corrosion from harsh cleaning chemicals.
2. Applications of JIS SUS304L Stainless Steel
Thanks to its corrosion resistance and low carbon content, JIS SUS304L stainless steel is used in industries where purity and durability matter most. Here are its top applications:
- Food Processing Equipment: Mixers, conveyor belts, and storage tanks. It meets food safety standards (like JIS Z 2801) and resists 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 (e.g., 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. 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. Resists 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. Handles heat and moisture without rust. A major appliance brand uses it for oven liners—lasts 10+ years with regular use.
3. Manufacturing Processes for JIS SUS304L Stainless Steel
JIS SUS304L stainless steel is easy to work with, making it popular for manufacturers. Here are the key manufacturing processes:
- Hot Rolling: Heated to 1100–1200°C and rolled into thick plates or bars. Used for large parts like tank shells. A steel mill in Japan uses hot rolling for SUS304L pipe blanks—ensures uniform strength.
- Cold Rolling: Done at room temperature to make thin sheets (e.g., appliance panels). Improves surface smoothness. A sheet metal factory uses cold rolling for SUS304L kitchen sink sheets—creates a sleek base for polishing.
- Annealing: Heated to 1010–1120°C and cooled slowly. Softens the steel after cold working (e.g., bending). A fabricator anneals SUS304L trim pieces—makes them easier to shape without cracking.
- Pickling: Treated with nitric acid to remove scale (from rolling or welding). Improves corrosion resistance. A pipe manufacturer pickles SUS304L pipes—ensures no rust spots before installation.
- Drawing: Pulled through dies to make wires or small tubes. Used for medical needles or electrical wires. A wire factory uses drawing for SUS304L medical wires—creates thin, flexible strands.
- Machining: Drilled, cut, or milled with high-speed steel (HSS) tools. Use coolant to avoid overheating. A machine shop machines SUS304L brackets—achieves precise holes for assembly.
4. Corrosion Resistance of JIS SUS304L Stainless Steel
The biggest advantage of JIS SUS304L stainless steel is its superior corrosion resistance—especially against intergranular corrosion. Here’s how it performs:
- Intergranular Corrosion Resistance: Low carbon (≤0.03%) prevents carbide precipitation (a cause of cracking in high heat). A chemical plant tested SUS304 vs. SUS304L in 600°C heat—SUS304 cracked in 3 months, while SUS304L stayed intact.
- Pitting Resistance: Resists small holes in mild chlorides (e.g., tap water). Tests show it withstands 150 ppm chloride levels without pitting.
- Crevice Corrosion: Performs well in tight spaces (e.g., bolted joints) if cleaned regularly. A marine equipment maker uses SUS304L for small fittings—no corrosion in saltwater spray (when rinsed weekly).
- Stress Corrosion Cracking: Resists cracking under stress + corrosion (e.g., pressure in pipes). A refinery uses it for fuel lines—no issues after 4 years of use.
- Surface Treatment for Extra Protection: Passivation (treating with acid) thickens the oxide layer. A food factory passivates SUS304L tanks—extends their life by 3x.
It’s not ideal for full seawater submersion (use SUS316L instead), but it works for coastal parts with regular maintenance.
5. Welding JIS SUS304L Stainless Steel
JIS SUS304L stainless steel has good weldability, but you need to follow best practices to avoid issues:
- Welding Processes: TIG (Tungsten Inert Gas) is best for thin parts (e.g., pipes), while MIG (Metal Inert Gas) works for thicker sections. A welder in Australia uses TIG for SUS304L medical device parts—creates clean, precise welds.
- Welding Rods: Use low-carbon fillers like AWS ER308L. Matching the filler to SUS304L’s low carbon prevents intergranular corrosion. A pipe welder once used ER308 (high carbon)—the weld cracked in 6 months.
- Welding Gases: Use argon (for TIG) or argon-CO₂ mixes (for MIG) to protect the weld from oxygen. This prevents oxidation and weak spots.
- Post-Weld Heat Treatment: Not always needed, but annealing at 1010–1120°C can remove stress. A structural fabricator anneals SUS304L welds for building brackets—ensures no cracking under load.
- Welding Inspection: Use X-ray or ultrasonic testing for critical parts (e.g., pharmaceutical tanks). A lab tests SUS304L welds—catches small defects before they cause leaks.
- Welding Safety: Wear heat-resistant gloves and a welding helmet—SUS304L produces bright sparks during welding.
6. Standards and Specifications for JIS SUS304L Stainless Steel
To ensure quality, JIS SUS304L stainless steel follows strict global standards. Here’s what you need to know:
- JIS G4303: The Japanese Industrial Standard for cold-rolled stainless steel sheets (covers SUS304L’s dimensions and composition).
- ASTM A240: The U.S. standard (equivalent to JIS SUS304L). You can use ASTM A240 Type 304L interchangeably with SUS304L.
- EN 10088: The European standard (EN 10088-2 X2CrNi18-10 is the equivalent grade).
- ISO Standards: ISO 15510 covers its chemical composition and mechanical properties for global projects.
- Material Certification: Ask for a mill certificate (e.g., MTC—Material Test Certificate) to verify compliance. A pharmaceutical client requires MTCs for all SUS304L parts—ensures purity for drug manufacturing.
- Quality Control: Manufacturers test for corrosion resistance, tensile strength, and carbon content. A steel supplier tests every batch of SUS304L—rejects batches that don’t meet standards.
7. Comparison with Other Materials
How does JIS SUS304L stainless steel stack up against other common materials? Here’s a clear comparison:
| Material | Key Advantage vs. SUS304L | Key Disadvantage vs. SUS304L | Best For |
|---|---|---|---|
| SUS304 | Lower cost (~5% cheaper) | Prone to intergranular corrosion | Non-heated applications (e.g., 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 (e.g., beams) |
| Duplex Stainless Steel | Higher strength | Less ductile (harder to form) | High-pressure pipes |
| Titanium Alloys | Extreme corrosion resistance | Very expensive (~5x cost) | Aerospace parts, deep-sea equipment |
| Aluminum Alloys | Lighter (density 2.7 g/cm³) | Less strong (tensile 276 MPa) | Lightweight parts (e.g., bike frames) |
For most high-heat or chemical applications (e.g., food processing, pharmaceuticals), SUS304L offers the best balance of cost and corrosion resistance.
Yigu Technology’s Perspective on JIS SUS304L Stainless Steel
At Yigu Technology, we recommend JIS SUS304L for clients in food, pharmaceutical, and chemical sectors. Its low carbon solves the intergranular corrosion issue that plagues SUS304, ensuring long-lasting performance. We help clients select the right manufacturing and welding methods to maximize its value—whether it’s for sterile medical devices or chemical pipes. While SUS316L is better for seawater, SUS304L remains the most cost-effective choice for 70% of our clients’ high-heat, corrosion-prone projects.
FAQ About JIS SUS304L Stainless Steel
- 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 JIS SUS304L be used in seawater?
It’s not ideal for full submersion (SUS316L is better for that). But it works for coastal parts (e.g., patio furniture) if you clean it monthly to remove salt spray—this prevents pitting. - Is JIS SUS304L easy to weld?
Yes! It has good weldability with TIG or MIG processes. Just use low-carbon filler rods (like AWS ER308L) and protect the weld with argon gas. For critical parts, add post-weld annealing to remove stress.
