X5CrNiCu17-4 is a copper-bearing martensitic precipitation-hardening (PH) stainless steel, the most widely used grade of the PH family. This datasheet presents the material within the Werkstoff-Nummer (DIN / EN) designation system.
With about 16% chromium, 4% nickel and 4% copper plus niobium, 1.4542 combines high strength and hardness with good corrosion resistance and ease of fabrication. It is supplied in the solution-treated condition and is strengthened by a single low-temperature ageing treatment that precipitates a copper-rich phase, with the strength level set by the ageing temperature. The alloy is magnetic. It should not be used above about 315 °C for prolonged periods.
Typical applications include aerospace, oil-and-gas and nuclear components, valve and pump parts, shafts, fasteners, gears, turbine blades and general high-strength corrosion-resistant hardware.
Typical values, age-hardened condition, per EN reference data.
| Property | Value | Unit |
|---|---|---|
| Density | 7.8 | g/cm³ |
| Melting range | 1400–1440 | °C |
| Elastic modulus | 197 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.8 | µm/m·°C |
| Thermal conductivity (20 °C) | 18.3 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Martensitic (precipitation-hardening) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 15.0 | 17.0 | Corrosion resistance; martensite former |
| Nickel | Ni | 3.0 | 5.0 | Toughness; martensite stability |
| Copper | Cu | 3.0 | 5.0 | Precipitation-hardening phase |
| Niobium | Nb | 0.15 | 0.45 | Carbide stabiliser; grain refinement |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 0.70 | Deoxidiser |
| Carbon | C | — | 0.07 | Strength; martensite hardness |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.015 | Residual impurity |
Typical values by ageing (P) condition, per EN 10088-3 / SEW 470 for W.Nr. 1.4542.
| Condition | Tensile strength (Rm) | 0.2% proof (Rp0.2) | Hardness |
|---|---|---|---|
| P1310 | ≥1310 MPa | ≥1180 MPa | ~44 HRC |
| P1070 | 1070–1270 MPa | ≥1000 MPa | ~35 HRC |
| P1000 | 1000–1200 MPa | ≥865 MPa | ~32 HRC |
| P930 | 930–1100 MPa | ≥725 MPa | ~28 HRC |
Values per EN 10088-3; confirm against the inspection certificate (EN 10204). Elongation typically ≥10–16 % depending on condition.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Good | Superior to martensitic 400-series |
| Mild acids (acetic, nitric, dilute) | Good | At low concentrations |
| Chloride pitting | Moderate | Lower than austenitic grades |
| Stress-corrosion cracking | Improved at higher ageing | Over-aged conditions give best SCC resistance |
| Seawater | Limited | Susceptible to pitting / crevice corrosion |
Corrosion resistance is roughly comparable to 1.4301 in many environments; behaviour improves with higher (over-aged) ageing conditions.
A martensitic precipitation-hardening alloy; supplied solution-treated and hardened by a single low-temperature ageing treatment.
Solution Treatment Approximately 1040 °C followed by cooling to room temperature to form a martensitic structure.
Precipitation Hardening (Ageing) A single low-temperature ageing treatment precipitates a copper-rich phase. The temperature sets the strength level: lower ageing temperatures give maximum strength; higher temperatures progressively lower strength while increasing toughness and stress-corrosion-cracking resistance. Air cool after ageing.
Weldable by common fusion and resistance methods; matching filler is used. A post-weld heat treatment (solution treat + age) restores corrosion resistance and full properties.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching 16-4-type filler |
| GMAW / MIG | Good | Matching filler |
| SMAW / stick | Good | Matching electrode |
Weld in the solution-treated or over-aged condition; re-age after welding to restore strength. Oxyacetylene welding is not recommended.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Solution-treated or over-aged for best machinability |
| Tooling | Carbide tooling; rigid setup |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Limited in hardened conditions; form solution-treated |
| Hot forming | ~1150–950 °C; solution treat + age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace | Structural fittings, engine parts, actuators | High strength + corrosion resistance |
| Oil & gas | Valve and pump components, shafts | Strength + corrosion resistance |
| Power generation | Turbine blades, shafts | Strength + moderate corrosion resistance |
| General industrial | Fasteners, gears, high-strength parts | Hardness + machinability |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Bar, rod and sections | EN 10088-3 · W.Nr. 1.4542 | X5CrNiCuNb16-4 |
| Forgings | EN 10250-3 · W.Nr. 1.4542 | — |
| Plate, sheet and strip | EN 10088-2 · W.Nr. 1.4542 | — |
| Technical delivery | SEW 470 | — |
Copper-bearing martensitic precipitation-hardening stainless steel. W.Nr. 1.4542 (X5CrNiCuNb16-4).
| EN Symbol | Cr % | Ni % | Cu % | Other | Best Used For |
|---|---|---|---|---|---|
| X5CrNiCu17-4 | 15–17 | 3–5 | 3–5 | Nb | General-purpose PH; high strength |
| X5CrNiCu15-5 | 14–15.5 | 3.5–5.5 | 2.5–4.5 | Nb | High-strength PH; transverse toughness |
| X3CrNiMoAl13-8-2 | 12.25–13.25 | 7.5–8.5 | — | Mo, Al | Highest-toughness PH; aerospace |
| X7CrNiAl17-7 | 16–18 | 6.5–7.8 | — | Al | Semi-austenitic PH; springs |
| X12Cr13 | 11.5–13.5 | — | — | — | Martensitic, lower strength |




