If you’ve ever shopped for kitchen sinks, food containers, or architectural trim, you’ve probably encountered JIS SUS304 stainless steel. It’s the most widely used stainless steel grade globally—thanks to its unbeatable mix of corrosion resistance, workability, and affordability. This guide breaks down everything you need to know to choose, use, and work with SUS304 for your projects.
1. Material Composition of JIS SUS304 Stainless Steel
The performance of JIS SUS304 stainless steel starts with its precise material composition. Every element is carefully balanced to deliver strength and corrosion resistance:
| Element | Content Range | Key Role |
|---|---|---|
| Chromium (Cr) | 18.0% – 20.0% | Forms a protective passivation layer (blocks rust and corrosion) |
| Nickel (Ni) | 8.0% – 10.5% | Stabilizes the austenitic microstructure (boosts ductility) |
| Carbon (C) | ≤0.08% | Limits carbide precipitation (prevents intergranular corrosion) |
| Manganese (Mn) | ≤2.0% | Improves workability during welding and forming |
| Silicon (Si) | ≤1.0% | Enhances heat resistance and reduces oxidation |
| Sulfur (S) | ≤0.03% | Minimizes brittleness (critical for machining) |
| Phosphorus (P) | ≤0.045% | Aids in cutting during machining (without harming durability) |
| Iron (Fe) | Balance | The base metal that holds all alloying elements together |
A real example: A food equipment manufacturer in Japan once used a low-chromium (16%) steel instead of SUS304. Their mixing bowls rusted within 3 months—switching to SUS304’s 18-20% chromium fixed the issue entirely.
2. Corrosion Resistance of JIS SUS304 Stainless Steel
JIS SUS304 stainless steel is famous for its reliable corrosion resistance—it works in most everyday and light industrial environments:
- Pitting resistance: Resists small holes (pitting) in mild chloride environments (e.g., tap water). Tests show it withstands up to 200 ppm chloride levels without pitting.
- Crevice corrosion: Performs well in tight spaces (e.g., bolted joints) if kept clean. A dairy in Australia uses SUS304 for milk pipe joints—no corrosion after 5 years of daily use.
- Intergranular corrosion: Low carbon content (≤0.08%) prevents this type of corrosion (common in high-heat applications like boilers).
- Stress corrosion cracking (SCC): Resists SCC in most environments, but avoid long-term exposure to high-temperature chlorides (e.g., saltwater above 60°C).
- Corrosion in acidic/alkaline environments: Handles dilute acids (e.g., vinegar) and bases (e.g., soap) well—ideal for food and cleaning equipment.
- Corrosion in seawater: Not recommended for full submersion (use SUS316 instead), but it works for coastal outdoor parts (e.g., patio furniture) with regular cleaning.
To maximize resistance, always perform passivation after fabrication—this thickens the protective chromium layer.
3. Mechanical Properties of JIS SUS304 Stainless Steel
JIS SUS304 stainless steel has well-rounded mechanical properties—strong enough for industrial use, yet flexible enough for forming:
| Property | Typical Value (Annealed) | Practical Benefit |
|---|---|---|
| Tensile strength | 515 MPa | Resists breaking under pressure (good for structural parts like handrails) |
| Yield strength | 205 MPa | Doesn’t bend easily (ideal for sinks or countertops) |
| Elongation | ≥40% | Bends and stretches without cracking (great for curved trim or pots) |
| Hardness | ≤201 HB (Brinell) | Soft enough for machining, but durable against scratches |
| Impact resistance | ≥68 J (at -196°C) | Doesn’t shatter in cold temperatures (suitable for frozen food equipment) |
| Modulus of elasticity | 193 GPa | Stiff enough for load-bearing parts (e.g., shelving) |
| Thermal expansion coefficient | 17.2 x 10⁻⁶/°C (20–100°C) | Minimal warping when heated (good for ovens or stovetops) |
A car manufacturer in South Korea uses SUS304 for exhaust trim. The steel’s high elongation lets them form it into sleek shapes, while its tensile strength ensures it lasts through years of vibration.
4. Applications of JIS SUS304 Stainless Steel
Thanks to its versatility, JIS SUS304 stainless steel is used in nearly every industry. Here are its most common applications:
- Food processing equipment: Mixers, tanks, and conveyor belts (meets food safety standards like FDA and JIS Z 2801). A bakery in France uses SUS304 for dough mixers—easy to clean and resistant to flour acids.
- Architectural applications: Handrails, facades, and roofing (looks sleek and resists weathering). A skyscraper in Tokyo used SUS304 for its exterior trim—still shiny after 10 years.
- Consumer appliances: Refrigerator doors, dishwasher interiors, and oven parts (handles heat and moisture). A major appliance brand uses SUS304 for dishwasher tubs—no rust from soapy water.
- Medical devices: Surgical trays and exam tables (easy to sterilize and non-toxic). A hospital in Singapore uses SUS304 for instrument carts—resists disinfectant corrosion.
- Industrial piping: Transporting water, chemicals, and gases (leak-proof and durable). A factory in China uses SUS304 pipes for freshwater supply—low maintenance for 8 years.
- Sanitary fittings: Faucets, showerheads, and sink drains (resists hard water stains). A hotel chain uses SUS304 faucets—no mineral buildup even in hard water areas.
5. Fabrication and Processing of JIS SUS304 Stainless Steel
JIS SUS304 stainless steel is easy to work with—making it a favorite for manufacturers. Here are key fabrication and processing methods:
- Welding techniques: TIG (best for thin parts like pipes) and MIG (faster for thick parts) work well. Use AWS ER308L filler wire to match SUS304’s composition.
- Machining methods: Drills, mills, and lathes cut SUS304 smoothly. Use high-speed steel (HSS) tools and coolant to avoid overheating.
- Forming processes: Deep drawing (for sinks), bending (for trim), and rolling (for sheets) are all possible—thanks to its high elongation.
- Heat treatment: Annealing at 1010–1120°C softens the steel after cold working (e.g., bending). Quench in water to restore ductility.
- Pickling & passivation: Pickle with nitric acid to remove weld scale; passivate to boost corrosion resistance. A fabricator in Germany skips passivation once—their parts rusted in 6 months.
- Laser/plasma cutting: Precise for complex shapes (e.g., decorative trim). A metal shop uses laser cutting to make SUS304 signage—clean edges with no extra finishing.
6. Surface Finishes of JIS SUS304 Stainless Steel
The right surface finish can enhance SUS304’s appearance and performance. Here are popular options:
- Polished finish: Shiny and reflective (Ra 0.05–0.1 μm). Used for kitchen sinks and decorative trim—adds a luxury look.
- Brushed finish: Matte with fine lines (Ra 0.4–1.6 μm). Resists fingerprints (great for appliances like refrigerators).
- Satin finish: Soft matte look (Ra 0.8–1.2 μm). Common in architectural parts like handrails—hides minor scratches.
- Mirror finish: Ultra-reflective (Ra ≤0.025 μm). Used for high-end decor (e.g., hotel lobbies) or optical parts.
- Sandblasted finish: Textured (Ra 2.0–5.0 μm). Provides grip (ideal for stair treads or industrial floors).
- Electrolytic polishing: Smooths and brightens the surface—improves corrosion resistance (used for medical devices).
A restaurant in Tokyo chose a brushed finish for their SUS304 countertops—easy to clean and no visible fingerprints from customers.
7. Comparison with Other Materials
How does JIS SUS304 stainless steel stack up against other common materials? Here’s a quick breakdown:
| Material | Key Advantage Over SUS304 | Key Disadvantage vs. SUS304 | Best For |
|---|---|---|---|
| SUS316 | Better seawater corrosion resistance | More expensive (~30% higher) | Marine parts, coastal architecture |
| Carbon steel | Lower cost (~50% cheaper) | No corrosion resistance | Structural parts (indoor, dry environments) |
| Aluminum | Lighter (density 2.7 g/cm³ vs. 7.9 g/cm³) | Less strong (tensile strength 276 MPa vs. 515 MPa) | Lightweight parts (e.g., bike frames) |
| Titanium | Extreme corrosion resistance | Very expensive (~5x cost) | Aerospace or medical implants |
| Brass | Warmer appearance | Tarnishes easily | Decorative hardware (e.g., doorknobs) |
For most general uses (e.g., food equipment, architecture), SUS304 offers the best balance of cost, performance, and ease of use.
Yigu Technology’s Perspective on JIS SUS304 Stainless Steel
At Yigu Technology, JIS SUS304 is our go-to recommendation for clients needing versatility and reliability. It works for everything from food machinery to architectural trim—solving common pain points like corrosion and poor workability. We help clients choose the right surface finish and fabrication methods to maximize SUS304’s value. While SUS316 is better for seawater, SUS304 remains the most cost-effective choice for 80% of everyday applications.
FAQ About JIS SUS304 Stainless Steel
- Is JIS SUS304 magnetic?
No—SUS304 has an austenitic microstructure, which makes it non-magnetic. This is a quick way to tell it apart from magnetic steels like SUS430 (ferritic) or SUS410 (martensitic). - Can JIS SUS304 be used outdoors?
Yes, but avoid full seawater submersion. For coastal areas, clean it every 3–6 months to remove salt spray. For inland outdoor parts (e.g., patio furniture), it will last decades with minimal maintenance. - How does JIS SUS304 compare to ASTM 304?
They are nearly identical! JIS SUS304 (Japanese standard) and ASTM 304 (U.S. standard) have the same chemical composition and mechanical properties—you can use them interchangeably in most projects.
