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 covers everything you need to know to choose, use, and work with SUS304 for your projects.
What is the material composition of SUS304?
The performance of JIS SUS304 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 protective passivation layer that blocks rust |
| Nickel (Ni) | 8.0% – 10.5% | Stabilizes 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, reduces oxidation |
| Sulfur (S) | ≤ 0.03% | Minimizes brittleness for machining |
| Phosphorus (P) | ≤ 0.045% | Aids cutting during machining without harming durability |
| Iron (Fe) | Balance | Base metal holding all alloying elements together |
A food equipment manufacturer in Japan once used low-chromium steel at 16% instead of SUS304. Their mixing bowls rusted within 3 months. Switching to SUS304’s 18–20% chromium fixed the issue entirely.
How does SUS304 resist corrosion?
JIS SUS304 is famous for its reliable corrosion resistance. It works in most everyday and light industrial environments.
- Pitting resistance: Resists small holes in mild chloride environments like tap water. Tests show it withstands up to 200 ppm chloride levels without pitting.
- Crevice corrosion: Performs well in tight spaces like 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 of ≤0.08% prevents this type of corrosion common in high-heat applications like boilers.
- Stress corrosion cracking (SCC): Resists SCC in most environments. Avoid long-term exposure to high-temperature chlorides like saltwater above 60°C.
- Acidic and alkaline environments: Handles dilute acids like vinegar and bases like soap well—ideal for food and cleaning equipment.
- Seawater: Not recommended for full submersion. Use SUS316 instead. Works for coastal outdoor parts like patio furniture with regular cleaning.
To maximize resistance, always perform passivation after fabrication. This thickens the protective chromium layer.
What are the mechanical properties of SUS304?
JIS SUS304 has well-rounded mechanical properties. It’s strong enough for industrial use yet flexible enough for forming.
| Property | Typical Value (Annealed) | Practical Benefit |
|---|---|---|
| Tensile strength | 515 MPa | Resists breaking under pressure |
| Yield strength | 205 MPa | Doesn’t bend easily |
| Elongation | ≥ 40% | Bends and stretches without cracking |
| Hardness | ≤ 201 HB | Soft enough for machining, durable against scratches |
| Impact resistance | ≥ 68 J at -196°C | Doesn’t shatter in cold temperatures |
| Modulus of elasticity | 193 GPa | Stiff enough for load-bearing parts |
| Thermal expansion | 17.2 × 10⁻⁶/°C (20–100°C) | Minimal warping when heated |
A car manufacturer in South Korea uses SUS304 for exhaust trim. The steel’s high elongation lets them form it into sleek shapes. Its tensile strength ensures it lasts through years of vibration.
Where is SUS304 used?
Thanks to its versatility, JIS SUS304 is used in nearly every industry. Here are its most common applications.
Food processing equipment
Mixers, tanks, and conveyor belts meet 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 look sleek and resist 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 handle heat and moisture. A major appliance brand uses SUS304 for dishwasher tubs—no rust from soapy water.
Medical devices
Surgical trays and exam tables are easy to sterilize and non-toxic. A hospital in Singapore uses SUS304 for instrument carts—resists disinfectant corrosion.
Industrial piping
Water, chemical, and gas transport pipes are 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 resist hard water stains. A hotel chain uses SUS304 faucets—no mineral buildup even in hard water areas.
How is SUS304 fabricated and processed?
JIS SUS304 is easy to work with, making it a favorite for manufacturers.
Welding techniques
TIG welding works best for thin parts like pipes. MIG welding is faster for thick parts. Use AWS ER308L filler wire to match SUS304’s composition.
Machining methods
Drills, mills, and lathes cut SUS304 smoothly. Use high-speed steel tools and coolant to avoid overheating.
Forming processes
Deep drawing for sinks, bending for trim, and rolling for sheets are all possible thanks to high elongation.
Heat treatment
Annealing at 1,010–1,120°C softens the steel after cold working like bending. Quench in water to restore ductility.
Pickling and passivation
Pickle with nitric acid to remove weld scale. Passivate to boost corrosion resistance. A fabricator in Germany skipped passivation once—their parts rusted in 6 months.
Laser and plasma cutting
Precise for complex shapes like decorative trim. A metal shop uses laser cutting to make SUS304 signage—clean edges with no extra finishing.
What surface finishes are available for SUS304?
The right surface finish can enhance SUS304’s appearance and performance.
| Finish | Characteristics | Typical Use |
|---|---|---|
| Polished | Shiny, reflective, Ra 0.05–0.1 μm | Kitchen sinks, decorative trim |
| Brushed | Matte with fine lines, Ra 0.4–1.6 μm | Appliances, resists fingerprints |
| Satin | Soft matte, Ra 0.8–1.2 μm | Handrails, hides minor scratches |
| Mirror | Ultra-reflective, Ra ≤ 0.025 μm | High-end decor, optical parts |
| Sandblasted | Textured, Ra 2.0–5.0 μm | Stair treads, industrial floors |
| Electrolytic polished | Smooth, brightened | Medical devices, improved corrosion resistance |
A restaurant in Tokyo chose a brushed finish for their SUS304 countertops. Easy to clean and no visible fingerprints from customers.
How does SUS304 compare to other materials?
Understanding how SUS304 stacks up helps with material selection.
| Material | Advantage Over SUS304 | Disadvantage vs. SUS304 | Best For |
|---|---|---|---|
| SUS316 | Better seawater corrosion resistance | 30% more expensive | Marine parts, coastal architecture |
| Carbon steel | 50% cheaper | No corrosion resistance | Indoor structural parts |
| Aluminum | Lighter at 2.7 vs. 7.9 g/cm³ | Lower tensile strength at 276 vs. 515 MPa | Lightweight parts like bike frames |
| Titanium | Extreme corrosion resistance | About 5 times more expensive | Aerospace, medical implants |
| Brass | Warmer appearance | Tarnishes easily | Decorative hardware like doorknobs |
For most general uses like food equipment and architecture, SUS304 offers the best balance of cost, performance, and ease of use.
Conclusion
JIS SUS304 stainless steel delivers reliable corrosion resistance, excellent formability, and affordable cost. Its 18–20% chromium content forms a protective passivation layer that blocks rust in most everyday environments. With high elongation for forming and good weldability for fabrication, it suits a wide range of applications from kitchen sinks to medical devices. While SUS316 is better for seawater exposure, SUS304 remains the most cost-effective choice for the majority of projects.
FAQ
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 or SUS410.
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 like patio furniture, it will last decades with minimal maintenance.
How does JIS SUS304 compare to ASTM 304?
They are nearly identical. JIS SUS304 follows Japanese standards, while ASTM 304 follows U.S. standards. They have the same chemical composition and mechanical properties. You can use them interchangeably in most projects.
Does SUS304 require special welding techniques?
Standard TIG and MIG welding work well. Use AWS ER308L filler wire to match the composition. No preheating is needed for most thicknesses. Post-weld passivation helps restore corrosion resistance.
Can SUS304 be used for high-temperature applications?
Yes, up to about 870°C for intermittent service and 925°C for continuous service. For higher temperatures, consider heat-resistant grades like SUS310.
Discuss Your Projects with Yigu Rapid Prototyping
At Yigu Rapid Prototyping, we help clients select and process the right stainless steel grades for their applications. From JIS SUS304 for food equipment and architectural trim to custom fabrication and finishing, our team brings practical experience to your project. Contact us to discuss your next build.