15-5PH
15 – 5PH (UNS S15500) is a widely used martensitic precipitation-hardening stainless steel, named after its key component ratios (≈15% Cr, ≈5% Ni-Cu). It forms a martensitic matrix after solution treatment, and copper-rich (Ni-Cu-Nb) precipitates are generated during aging to achieve strengthening. It combines corrosion resistance close to 304 stainless steel with ultra-high mechanical properties (tensile strength 860 – 1275 MPa based on aging conditions) and maintains stable performance in the temperature range of -55 °C to 315 °C. These characteristics make it an ideal choice for scenarios requiring high strength, corrosion resistance, and precise dimensional control.
- UNS
- S15500
- Europe
- EN 1.4545, DIN X5CrNiCuNb15 – 5
- China
- 05Cr15Ni5Cu4Nb (per GB/T 20878 standard)
- Density
- 7.75 g/cm³
- Melting range
- 1420 – 1460 °C
- Delivery
- Annealed and pickled, or cold-rolled bright; cut to length.
What the spec says
Chemical composition in weight per cent and the standards we routinely certify to. Governing values are those printed on the EN 10204 certificate for your heat.
| Element | % |
|---|---|
| C | ≤ 0.07 |
| Cr | 14.0-15.5 |
| Ni | 3.5-5.5 |
| Cu | 2.5-4.5 |
| Nb | 0.15-0.45 |
| Si | ≤ 1.00 |
| Mn | ≤ 1.00 |
| P | ≤ 0.040 |
| S | ≤ 0.030 |
| Fe | Balance |
| Form | Standard |
|---|---|
| Plates/Sheets | ASTM A693 (Grade S15500), AMS 5862, GB/T 4237. |
| Round Bars | ASTM A564 (Grade S15500), AMS5659, GB/T 1220, EN 10088 – 3. |
| Forgings | ASTM A705/A705M (Grade S15500), EN 10222 – 5. |
Behaviour that matters in service
- Precipitation Hardening Mechanism — No quenching and tempering process (required for traditional martensitic steels) is needed. Strengthening is achieved through "solution treatment (1040 °C) + aging treatment" (common conditions: H900, H1025, H1150, H1100M), enabling flexible adjustment of the strength-toughness balance.
- Superior Strength-Corrosion Balance — The yield strength in H900 condition is ≥860 MPa, which is 2 – 3 times that of 304/316L. Its corrosion resistance is comparable to 304 (resistant to atmospheric, fresh water, and mild acid/alkali corrosion), and its stress corrosion cracking resistance is superior to 17 – 4PH.
- Excellent Toughness & Dimensional Stability. — It exhibits outstanding low-temperature toughness (impact energy ≥68 J at -55 °C) and minimal deformation during heat treatment, meeting the requirements of high-precision components.
- Good Processability — In the soft solution-annealed state, its machinability is better than that of austenitic stainless steels. It is compatible with TIG/MIG welding, and post-weld aging is recommended to restore strength.
- Medium-Temperature Adaptability — It maintains stable performance at temperatures ≤315 °C; above 315 °C, precipitates coarsen, leading to a decrease in strength.
- Optimized Toughness Performance — Compared with 17 – 4PH, 15 – 5PH has better fracture toughness and fatigue resistance at the same strength level.
Typical applications
How we ship 15-5PH
Melted in our own furnaces, tested in our own laboratory, and released with a certificate that matches the stamping on the bar or plate.
Forms
Round bar from 6 mm, plate, strip, seamless tube, open-die forgings and drawn wire.
Condition
Annealed and pickled, or cold-rolled bright; cut to length.
Documents
EN 10204 3.1 or 3.2, with chemistry, mechanical results and heat number traceability.
Inspection
SGS, BV, Intertek or your own inspector — welcomed before shipment.
Send the grade, the size, the quantity.
We will quote 15-5PH against your specification — including lead time, inspection level and documents.