Material number S30400: 304
S30400 is the Unified Numbering System designation for 304, austenitic chromium-nickel stainless steel specified in ASTM A240.
Reading S30400 digit by digit
A UNS designation (ASTM E527 / SAE J1086) is a letter followed by five digits. The letter S marks the alloy family — here stainless and heat-resisting steels — and the five digits 30400 place the composition inside it, usually by carrying an older AISI or SAE number forward.
What a UNS number does not carry is the product form or the property level. S30400 therefore appears in several ASTM specifications — plate, bar, pipe, forging — each with its own mechanical requirements, and the number alone is not a complete purchase specification.
S30400 identity card
| Item | Value |
|---|---|
| UNS number (ASTM E527) | S30400 |
| Symbolic grade name | 304 |
| Steel group | S — stainless and heat-resisting steels |
| Sequential number in group | 30400 |
| Specified in | ASTM A240 |
| Steel family | Stainless steel |
| Yield, first condition in the table | ≥ 205 MPa (Plate, sheet, strip — annealed (A240)) |
| Tensile, same condition | ≥ 515 MPa |
| Cross-references held | 10 grades in 7 systems |
304 stainless steel (UNS S30400, 18-8): 18 % Cr, 8 % Ni, ≤ 0.08 % C. 205 MPa (30 ksi) yield, 515 MPa (75 ksi) tensile, non-magnetic, food-safe. Composition, properties, 304 vs 304L vs 316, and 1.4301/SUS304 equivalents.
Full data sheet for 304 → · Equivalent grades → · ASTM A240 →
UNS S — the neighbouring numbers
| UNS number | Grade | Type |
|---|---|---|
| S17400 | 17-4 PH | Martensitic precipitation-hardening stainless steel |
| S30403 | 304L | Low-carbon austenitic chromium-nickel stainless steel |
| S31000 | 310 | Austenitic heat-resisting stainless steel (25 % Cr, 20 % Ni) |
| S31600 | 316 | Austenitic chromium-nickel-molybdenum stainless steel |
| S31603 | 316L | Low-carbon austenitic chromium-nickel-molybdenum stainless steel |
| S32100 | 321 | Austenitic Cr-Ni stainless steel, titanium-stabilized |
| S32205 | 2205 | Ferritic-austenitic (duplex) stainless steel |
| S41000 | 410 | Martensitic chromium stainless steel, hardenable |
| S43000 | 430 | Ferritic chromium stainless steel |
Same UNS letter, so the same alloy family. The digits generally carry an older AISI or SAE number.