Material number S17400: 17-4 PH
S17400 is the Unified Numbering System designation for 17-4 PH, martensitic precipitation-hardening stainless steel specified in ASTM A564.
Reading S17400 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 17400 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. S17400 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.
S17400 identity card
| Item | Value |
|---|---|
| UNS number (ASTM E527) | S17400 |
| Symbolic grade name | 17-4 PH |
| Steel group | S — stainless and heat-resisting steels |
| Sequential number in group | 17400 |
| Specified in | ASTM A564 |
| Steel family | Stainless steel |
| Yield, first condition in the table | ≈ 760 (typ.) MPa (Condition A (solution annealed 1040 °C) — as supplied) |
| Tensile, same condition | ≈ 1030 (typ.) MPa |
| Cross-references held | 8 grades in 5 systems |
17-4 PH stainless steel (UNS S17400, Type 630, EN 1.4542): 15–17.5 % Cr, 3–5 % Ni, 3–5 % Cu, Nb. Age-hardened H900 to 1170 MPa yield / 1310 MPa tensile, 40–47 HRC; H1150 for toughness. Heat-treatment conditions, properties, 1.4542/SUS630 equivalents.
Full data sheet for 17-4 PH → · Equivalent grades → · ASTM A564 →
UNS S — the neighbouring numbers
| UNS number | Grade | Type |
|---|---|---|
| S30400 | 304 | Austenitic chromium-nickel 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.