304 stainless steel wire is a general-purpose, corrosion-resistant 18/8 chromium-nickel wire sold under the designation UNS S30400.
Specifying the wrong grade is how a spring loses its tension or a wire part corrodes early in service. What is 304 stainless steel wire comes down to one alloy with predictable chemistry, plus a handful of supplier-dependent choices—temper, finish, and diameter tolerance—that decide how it behaves.
What Is In 304 Stainless Steel Wire?
Alloy 304 is the workhorse of the stainless family. Its roughly 18% chromium and 8% nickel content—the “18/8” ratio—gives it good corrosion resistance and formability, and it is widely sold in round-wire form under international designations including 1.4301 and SUS 304. This is the alloy most general-purpose wire orders are built around.
Typical chemistry and physical properties of alloy 304 wire
| Property | Typical Reported Value | Why It Matters |
|---|---|---|
| Chromium | 17.50–19.50% | Forms a self-healing oxide film that resists rust |
| Nickel | 8.00–10.50% | Stabilizes the austenitic structure for forming and welding |
| Carbon | 0.07–0.08% max | Keeps the alloy ductile and weld-friendly |
| Manganese, phosphorus, sulfur, silicon | 2.00, 0.045, 0.030, 1.00% max | Controls toughness and cleanliness during wire drawing |
| Melting point | About 1400–1455 °C (≈2650 °F) | Sets a ceiling for heat exposure |
| Density | 8.0 g/cm³ (0.29 lb/in³) | Used for weight and cost estimates |
| Modulus of elasticity | 190–210 GPa | Predicts spring rate and deflection |
How Is 304 Stainless Steel Wire Supplied?
Vendors sell the alloy in a controlled range of sizes and conditions. Ulbrich’s 304 alloy page, a specialist mill source, lists round wire from 0.015 in to 0.500 in (about 0.1–10 mm), meaning the practical range spans fine mesh all the way to thick formed parts. Published listing shows these variables:
- Tempers: soft, half hard, 3/4 hard, and full hard—each trades formability against finished strength.
- Finishes: bright, soap coated, and sometimes electropolished for cleaner surfaces.
- Diameter tolerance: varies by supplier and drawn-wire standard, so tight-tolerance jobs need the spec confirmed up front.
Standards come into play mainly for spring and critical applications. Published wire listings cite ASTM A313 for spring wire, ASTM A580 for general stainless steel wire, plus AMS 5688 in aerospace contexts and the usual international equivalents (JIS G4309, EN 10088-3, GB/T 4240).
Limits To Check Before You Specify It
Two practical limits catch buyers off guard: heat and magnetism. Temperature figures for 304 spring wire are supplier-specific, not universal—one Ulbrich data sheet lists a 500°F maximum operating temperature, while Ulbrich’s 304 alloy page serves as the clean reference for the datasheet range. Treat any single “max temp” as a starting point rather than a fixed rule.
Buying 304 Stainless Steel Wire That Matches The Job
Treat “304 stainless steel wire” as a family name, not one universal product. Exact chemistry, temper, finish, diameter tolerance, and allowable temperature vary by vendor and product standard, so the smart order starts with the supplier’s spec sheet in hand. Most general-purpose work is well served by 304, but if a part will sit in marine or chloride-heavy environments, step up to 316 instead.
When you shop, the first comparison to make is temper, then finish. For a side-by-side look at what is selling well right now, our roundup of the best 304 stainless steel wire options rates current picks by diameter range, finish, and documented specs.
FAQs
Is 304 stainless steel wire magnetic?
In the annealed (soft) condition, 304 is austenitic and essentially nonmagnetic. Cold drawing to spring temper can convert part of the structure to martensite, so a fully hard wire may show a slight magnetic pull. If the application demands a completely nonmagnetic wire, verify the temper with the supplier before ordering.
What is the difference between 304 and 316 stainless wire?
Both are austenitic stainless steels, but 316 adds molybdenum, which improves resistance to chlorides and saltwater. For ordinary indoor or light outdoor use, 304 delivers the same corrosion resistance at a lower price; for marine environments or chemical exposure, 316 is the safer choice.
Can 304 stainless steel wire be used for springs?
Yes. In spring temper, 304 wire is a standard general-purpose spring material with good corrosion resistance and formability, often supplied to the ASTM A313 spring-wire standard. Maximum service temperature is usually listed between 500°F and 550°F, depending on the supplier, so high-heat applications need a higher-alloy wire.
References & Sources
- Ulbrich Stainless Steels & Special Metals. “304 Stainless Steel Wire (UNS S30400).” Supplier alloy page covering chemistry, physical properties, standards, and wire sizes.
- Alloy Wire International. “Stainless Steel Alloy 304.” Datasheet and listing for 304 wire tempers, finishes, and dimensions.