1.4543 is a titanium-, copper- and niobium-bearing martensitic age-hardenable (precipitation-hardening) stainless steel. This datasheet presents the material within the Werkstoff-Nummer (DIN / EN) designation system.
With about 12% chromium, 9% nickel, 2% copper, titanium and niobium, 1.4543 develops exceptionally high proof strength — roughly three times that of standard austenitic grades — after a single low-temperature ageing treatment, while retaining good ductility, toughness and moderate corrosion resistance. It is relatively soft and formable in the solution-treated condition and has a very low work-hardening rate, permitting extensive cold forming with minimal dimensional change on hardening.
Typical applications include aerospace structural components, shafting, valve and pump parts, fasteners, springs, and high-strength corrosion-resistant hardware.
Typical values, precipitation-hardened condition, per EN reference data.
| Property | Value | Unit |
|---|---|---|
| Density | 7.76 | g/cm³ |
| Melting range | 1400–1440 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 10.2 | µm/m·°C |
| Thermal conductivity (20 °C) | 17.0 | 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 | 11.0 | 12.5 | Corrosion resistance; martensite former |
| Nickel | Ni | 7.5 | 9.5 | Toughness; martensite stability |
| Copper | Cu | 1.5 | 2.5 | Precipitation-hardening phase |
| Titanium | Ti | 0.80 | 1.40 | Precipitation-hardening phase |
| Niobium | Nb | 0.10 | 0.50 | Carbide stabiliser; precipitation |
| Manganese | Mn | — | 0.50 | Deoxidiser |
| Silicon | Si | — | 0.50 | Deoxidiser |
| Carbon | C | — | 0.05 | Low (toughness) |
| 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. 1.4543.
| Condition | Tensile strength (Rm) | 0.2% proof (Rp0.2) | Hardness |
|---|---|---|---|
| +P1600 (H900) | ≥1655 MPa | ≥1585 MPa | ~49 HRC |
| +P1550 (H950) | ≥1620 MPa | ≥1520 MPa | ~48 HRC |
| +P1500 (H1000) | ≥1520 MPa | ≥1410 MPa | ~44 HRC |
| +AT (solution-annealed) | ~1000 MPa | ~795 MPa | ~30–35 HRC |
Values per EN 10088-3; confirm against the inspection certificate (EN 10204). Elongation typically ≥8–12 % in hardened conditions.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Moderate to Good | Between 1.4542 and martensitic 400-series |
| Mild acids | Moderate | At low concentrations |
| Chloride pitting | Moderate | Lower than austenitic grades |
| Stress-corrosion cracking | Moderate | Improved at higher ageing |
| Seawater | Limited | Not recommended for prolonged exposure |
Corrosion resistance is moderate — adequate for many structural applications but below the higher-chromium PH grades; the alloy is selected primarily for its ultra-high strength.
A martensitic precipitation-hardening alloy; supplied solution-treated and hardened by a single low-temperature ageing treatment.
Solution Treatment Approximately 830 °C, hold, then cool to room temperature to form a soft martensitic structure. Generally supplied solution-annealed.
Precipitation Hardening (Ageing) A single ageing treatment develops ultra-high strength: lower ageing temperatures give maximum strength; higher temperatures progressively lower strength while increasing toughness. Cold work prior to ageing further raises strength. Air cool after ageing; minimal dimensional change.
Weldable in much the same manner as other precipitation-hardenable stainless steels; matching filler is used. A post-weld heat treatment restores full properties.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching 12-9-type filler |
| GMAW / MIG | Good | Matching filler |
| SMAW / stick | Good | Matching electrode |
Weld in the solution-treated condition; re-age after welding to restore strength.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Solution-treated (machinable; close-tolerance possible) |
| Work hardening | Very low rate — allows extensive cold forming |
| Tooling | Carbide tooling; rigid setup |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Extensive cold forming, cold drawing, cold-heading (very low work-hardening rate) |
| Hot forming | ~1150–950 °C; solution treat + age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace | Structural fittings, shafts, actuators | Ultra-high strength + fabricability |
| Defence | High-strength structural components | Strength + toughness |
| Sporting goods | High-strength shafts | Strength-to-weight |
| General industrial | High-strength fasteners, springs | Hardness + cold formability |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Bar, rod and sections | EN 10088-3 · W.Nr. 1.4543 | X3CrNiCuTiNb12-9 |
| Forgings | EN 10250-3 · W.Nr. 1.4543 | — |
| Plate, sheet and strip | EN 10088-2 · W.Nr. 1.4543 | — |
| Technical delivery | SEW 470 | — |
Titanium-, copper- and niobium-bearing martensitic precipitation-hardening stainless steel. W.Nr. 1.4543 (X3CrNiCuTiNb12-9).
| W.Nr. | Cr % | Ni % | Cu % | Other | Best Used For |
|---|---|---|---|---|---|
| 1.4543 | 11–12.5 | 7.5–9.5 | 1.5–2.5 | Ti, Nb | Ultra-high-strength PH; fabricable |
| 1.4594 | 14–16 | 5–7 | 1.25–1.75 | Mo, Nb | PH with 304-like corrosion resistance |
| 1.4542 | 15–17 | 3–5 | 3–5 | Nb | General-purpose martensitic PH |
| 1.4534 | 12.25–13.25 | 7.5–8.5 | — | Mo, Al | Highest-toughness PH; aerospace |
| 1.4006 | 11.5–13.5 | — | — | — | Martensitic, lower strength |




