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Materials
SUS304 stainless steel for stamping and sheet metal
SUS304 is the JIS name for austenitic 18% chromium, 8% nickel stainless steel, equivalent to AISI 304, UNS S30400 and EN 1.4301. It resists corrosion without coating, forms and welds well, and is non-magnetic when annealed. We stamp it from 0.5 mm coil and laser cut, bend and weld it as sheet.
Key specs at a glance
| Standard | JIS G 4305 (cold-rolled sheet/strip), JIS G 4313 (spring strip) |
|---|---|
| Equivalents | AISI 304, UNS S30400, EN 1.4301, GB 06Cr19Ni10 |
| In production at Sierxi | 0.5 mm coil for stamping; sheet for fabrication |
| Processes | Stamping, laser cutting, CNC bending, laser welding |
What is SUS304?
SUS304 is an austenitic chromium-nickel stainless steel. The chromium forms a thin passive oxide layer that protects the surface, so parts can be used bare in most indoor and many outdoor environments. It is the most widely used stainless grade, which makes coil and sheet easy to source in many thicknesses and finishes.
| Element | JIS G 4305 range (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Chromium (Cr) | 18.00–20.00 |
| Nickel (Ni) | 8.00–10.50 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
Typical mechanical and physical properties
| Property | Typical value |
|---|---|
| Tensile strength (annealed, JIS G 4305) | ≥ 520 N/mm² |
| 0.2% proof stress (annealed) | ≥ 205 N/mm² |
| Elongation (annealed) | ≥ 40% |
| Hardness (annealed) | ≤ 200 HV |
| Density | about 7.93 g/cm³ |
| Elastic modulus | about 193 GPa |
| Thermal conductivity | about 16 W/m·K |
Which temper should you specify for stamped parts?
Annealed SUS304 is soft and very formable — right for brackets, covers and deep bends. For clips, spring contacts and thin covers that must hold their shape, a cold-rolled temper from JIS G 4313 spring strip (SUS304-CSP) is used. Typical tempers are 1/2H, 3/4H and H; harder tempers give more spring force but need larger bend radii and crack more easily across the rolling direction.
Put the temper or the required hardness on the drawing, not just “SUS304”. Otherwise most suppliers will quote annealed material, and your clip may not hold its spring force.
Design rules for SUS304 parts
- Inside bend radius of at least about 1 × t for annealed sheet; larger for 1/2H and harder tempers.
- Allow for springback: SUS304 springs back more than SPCC, so bends are over-bent and checked on first pieces.
- Hole diameter of at least about 1.5 × t for punched holes to protect punches.
- Orient tight bends across the rolling direction where possible on hard tempers, or ask us to review the strip layout.
- Mark cosmetic faces; brushed and bright finishes scratch and are supplied with protective film.
Is SUS304 magnetic?
Annealed SUS304 is essentially non-magnetic. Cold work — rolling to a hard temper, stamping or bending — transforms some austenite to martensite, so formed areas can become slightly magnetic. If a part must be non-magnetic, say so on the drawing; harder tempers and heavily formed features are where it shows.
Finishes and corrosion
Common sheet finishes are 2B (smooth matt), BA (bright annealed), No.4 and HL (brushed). After welding or heavy machining, pickling and passivation restore corrosion resistance; we arrange this with qualified finishing partners. In chloride environments such as coastal sites or de-icing salt, consider SUS316 instead.
How to call out SUS304 on a drawing
- Grade and standard: for example “SUS304 (JIS G 4305)” or “SUS304-CSP 1/2H (JIS G 4313)”
- Thickness and tolerance
- Surface finish (2B, BA, No.4, HL) and which faces are cosmetic
- Passivation requirement, if any
- Non-magnetic requirement, if any
Frequently asked questions
Is SUS304 the same as AISI 304?
They are equivalent grades with closely matching chemistry. SUS304 is the JIS designation, 304 the AISI/ASTM one and 1.4301 the European number. See our equivalents table for other standards.
Can SUS304 be soldered?
It can, but it needs an aggressive flux and is harder to solder than nickel silver or tin-plated steel. For solder-mounted shielding cans we usually suggest C7701 nickel silver.
Does SUS304 need plating?
Usually not. It is used bare, brushed or passivated. Plating is only needed for special contact or solderability requirements.
What SUS304 thickness can you stamp?
We currently run 0.5 mm SUS304 coil; our stamping range is 0.15–1.2 mm. Thicker stainless is laser cut and bent.
Related pages
Materials
JIS, ASTM and GB material equivalents
Equivalent grades for SPCC, SGCC, SUS304, A5052 and C7701 across JIS, ASTM/UNS, EN and Chinese GB standards, for stamping and sheet metal.
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