JIS SUS304 Stainless Steel: The Ultimate Guide to Properties, Uses & More

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.

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.

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.

A restaurant in Tokyo chose a brushed finish for their SUS304 countertops. Easy to clean and no visible fingerprints from customers.

How to write a spec that gets priced correctly

A drawing is a contract. If it leaves a number open, the shop fills that number in with its own default. The default is rarely the one you had in mind. Put these five lines on every RFQ and most of the back-and-forth disappears before it starts.

• Alloy designation and the standard behind it
• Temper or heat treatment condition
• Mechanical properties you actually need
• Mill certificate and traceability requirement
• Finish and the faces it applies to

The point is not paperwork. Each line removes a decision the shop would otherwise make for you. A complete RFQ comes back priced. An incomplete one comes back guessed.

What actually drives the price

Buyers usually push on material because it is the line they can see. In practice the material is rarely the biggest number on a quote. These five lines decide most of it:

• alloy grade and mill availability
• stock size versus finished size
• heat treatment and testing
• machinability
• certification

Ask for the quote split by line. A supplier who cannot break it down is guessing, and you will pay for the guess. The line you can usually renegotiate is the tolerance band, not the raw material.

Problems you will meet, and the fix

Every process has a failure mode it prefers. The same four show up again and again on this kind of work, and none of them are mysteries once you know what to look for.

• Substituting a similar grade without telling anyone
• Hardness that varies across a single bar
• Corrosion in a weld heat-affected zone
• Distortion after heat treatment on a thin part

Catch the fault on the first part, not the hundredth. A first-article check costs an hour. A bad batch costs the whole order. Write the check into the purchase order so nobody has to remember it.

What to check on the first article

The first article is the cheapest inspection you will ever buy. Use it properly and the rest of the run becomes boring, which is exactly what you want.

• Every dimension on the drawing, with the measured value written beside it.
• The material certificate, matched to the heat or lot number on the parts.
• The finish against the sample you approved, under the same light.
• Fit against the mating part, assembled rather than measured.
• Packaging, because parts that arrive damaged were never in tolerance.

Check in this order: datums, then mating features, then cosmetic faces. If the datums are wrong, every number after them is noise. Keep the report on file. When a problem shows up in month six, that document is the only thing that tells you what changed.

How to compare two quotes fairly

Two numbers are not comparable unless the scope matches. Line them up before you decide, because a low number with three gaps is not a low number.

Same drawing, same material, same finish, same inspection. Anything else is a different job wearing the same part number. Then look at what each quote leaves out. Freight, packaging, certificates and tooling are the usual gaps.

Ask each supplier to state their assumptions in writing. The one who does is usually the one who has run the process before.

Scaling from one part to a batch

The first part teaches you the process. The hundredth teaches you the process cost.

Watch three things as volume grows: setup amortisation, tool wear, and how much hand work the finish still needs. If the unit price barely moves between ten and a hundred, the cost sits in material or in hand work, not in setup. Ask which, because only one of them is negotiable.

Lead time behaves the same way. A one-off is scheduled around other jobs. A repeat order is scheduled around your forecast. Give the shop a forecast and the lead time gets shorter, not longer.

How to read a supplier's quote

A quote is a short document with a long shadow. Four things in it decide whether the job runs smoothly, and only one of them is the price.

• The scope line. It should name the process, the material and the finish, not just the part.
• The tolerance basis. General tolerance or the drawing, and which standard it follows.
• The exclusions. Tooling, freight, certificates and inspection are the usual omissions.
• The validity date. Material prices move, and an open-ended quote is a promise nobody can keep.

Read the exclusions before you read the total. A quote that leaves out tooling is not cheaper. It is a quote for a different job.

What to send with the first order

The first order sets the pattern for every order after it. Send a complete package once and the shop files it, and the second order takes a fraction of the time.

• A STEP or native model plus a PDF drawing carrying the same revision letter.
• The material callout by standard number, not by trade name.
• The finish and the exact faces it applies to.
• Any test the part must pass: fit, seal, drop, salt spray, dielectric.
• A contact who can answer a question inside one working day.

Then write down what was agreed. An email that confirms the material, the finish and the date is worth more than a longer purchase order that leaves them open.

When this is the wrong choice

A good supplier tells you when the process does not fit. These are the cases where we say so.

• The volume is so low that setup costs more than the parts are worth.
• The tolerance is tighter than the process can hold without a second operation.
• The geometry cannot be made without a tool feature that will not pay back.
• The material you need is not available in the form the process requires.
• The schedule is shorter than the tooling or setup time, and nobody has said so yet.

None of these are refusals. They are reasons to look at a different route, and the earlier that conversation happens the cheaper it is. The most expensive mistake in manufacturing is a process chosen before the question was understood.

Planning the ramp from prototype to production

The gap between one good part and a thousand identical ones is a plan, not a machine. Three decisions close it.

First, freeze the design. Every change after tooling starts is a re-cut, and re-cuts are where schedules go. Second, decide the inspection level. A prototype is checked by eye; a production part is checked against a report. Third, agree the change process in writing, including who pays for it.

Write the ramp down as dates and owners, not as intentions. A ramp plan with three names and three dates is worth more than a page of good intentions.

What documentation to expect

Paperwork is not bureaucracy when a part fails at the customer. It is the only record of what was agreed. A normal shipment should carry four documents.

• A dimensional report covering every callout on the drawing.
• A material certificate traceable to the heat or lot number.
• A finish or coating certificate where the specification requires one.
• A packing list that matches the carton labels.

If a supplier cannot produce these on request, they are not running a controlled process. Ask for one sample set before you place the first order and you will know exactly what you are buying.

How does SUS304 compare to other materials?

Understanding how SUS304 stacks up helps with material selection.

For most general uses like food equipment and architecture, SUS304 offers the best balance of cost, performance, and ease of use.

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.

Our solution for JIS SUS304 Stainless Steel

YiguProto runs metal sourcing and machining in house, from a single prototype to a production batch. We quote the process, the material and the finish as separate lines, so you can see where the money goes instead of arguing with one number.

Send a STEP file or a drawing and you get a DFM report in one to two business days. It flags the features that add cost and the features that will not hold tolerance on the process you picked.

Every order ships with an inspection report on the features you call out. If a part misses, we make it again. Ready to price a part? Start with a free quote and DFM review, or read more about our metal sourcing and machining. You can also talk to an engineer before you commit to a drawing.

FAQ about JIS SUS304 Stainless Steel

The short version

JIS SUS304 Stainless Steel rewards the buyer who reads the data sheet and the drawing together. Pick the option for the property that matters, not for the price per kilo.

Tighten only what mates. Test a sample before the run. Then let the process do the rest.