PH grades / UNS S17400
17-4 PH (UNS S17400, Type 630) is a martensitic precipitation-hardening stainless steel. A single low-temperature ageing treatment raises strength to over 1,300 MPa while keeping corrosion resistance similar to 304.
- UNS S17400
- W.Nr. 1.4542
- Spec ASTM A564 / A693
- Density 7.78 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | S17400 |
| W.Nr. | 1.4542 |
| EN | X5CrNiCuNb16-4 |
| JIS | SUS630 |
| Also known as | 630, SUS630, 1.4542, X5CrNiCuNb16-4, 17-4PH |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| C | — | 0.07 |
| Mn | — | 1.00 |
| P | — | 0.040 |
| S | — | 0.030 |
| Si | — | 1.00 |
| Cr | 15.0 | 17.5 |
| Ni | 3.0 | 5.0 |
| Cu | 3.0 | 5.0 |
| Nb+Ta | 0.15 | 0.45 |
| Fe | Bal. | — |
Heat treatment / condition
| Condition | Ageing | Tensile, MPa | Yield 0.2%, MPa | Elongation, % | Hardness, HRC |
|---|---|---|---|---|---|
| H900 | 482 °C, 1 h | 1310 | 1170 | 10 | 40 min |
| H1025 | 552 °C, 4 h | 1070 | 1000 | 12 | 35 min |
| H1075 | 579 °C, 4 h | 1000 | 860 | 13 | 32 min |
| H1150 | 621 °C, 4 h | 930 | 725 | 16 | 28 min |
| H1150D | Double age, 621 °C | 862 | 724 | 16 | 24–33 |
| H1150M | 760 °C + 621 °C | 793 | 517 | 18 | — |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.78 g/cm³ | 0.281 lb/in³ |
| Magnetic response | Magnetic | — |
Available forms & specifications
| Form | Specification | Size range |
|---|---|---|
| Sheets, plates & strip | ASTM A693 | 0.3 mm – 6 mm |
| Bars & wire | ASTM A564 / ASME SA564 | 3 mm – 500 mm |
| Forgings | ASTM A705 / ASME SA705 | 1/2" – 48" NB (larger on request) |
Corrosion & temperature resistance
Corrosion resistance is broadly comparable to 304 in most environments. Higher ageing temperatures (H1100, H1150, H1150D/M) lower strength but improve toughness and resistance to stress-corrosion cracking.
Applications
17-4 PH: Shafts, valve parts, aerospace, fasteners. Pump and valve shafts, oilfield and aerospace components, gears, fasteners, moulds and high-strength fittings.
17-4 PH vs 13-8 Mo
| 17-4 PH | 13-8 Mo | |
|---|---|---|
| UNS | S17400 | S13800 |
| Key property | High strength + stainless corrosion resistance | Very high strength, good toughness |
| Typical use | Shafts, valve parts, aerospace, fasteners | Aerospace structures, landing gear, nuclear |
| Cr (wt %) | 15.0–17.5 | 12.25–13.25 |
| Ni (wt %) | 3.0–5.0 | 7.5–8.5 |
| Mo (wt %) | — | 2.0–2.5 |
| C (wt %) | ≤ 0.07 | ≤ 0.05 |
| Tensile / yield (min, MPa) | — | — |
Frequently asked questions
What is the UNS number of 17-4 PH?
17-4 PH is designated UNS S17400 (W.Nr. 1.4542, EN X5CrNiCuNb16-4).
What is 17-4 PH used for?
High strength + stainless corrosion resistance. Typical uses: shafts, valve parts, aerospace, fasteners.
Is 17-4 PH magnetic?
Magnetic.
In which forms can I buy 17-4 PH from Rajkamal Metals?
Coils & Strips, Sheets & Plates, Round Bars & Rods, Fasteners. Sizes as per standard; other sizes on request.
Do you supply a Mill Test Certificate with 17-4 PH?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
What is the difference between 17-4 PH and 13-8 Mo?
17-4 PH: high strength + stainless corrosion resistance. 13-8 Mo: very high strength, good toughness. See the comparison table on this page.
Last updated: 30 October 2026. Grade names identify the supply range; designations are not engineering equivalents. Availability, make, origin and documentation are confirmed at quotation.
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