X5CrNiCuNb16-4
Precipitation-hardening martensitic stainless steel. Reaches strengths above 1000 MPa by ageing, with corrosion resistance close to 304; the classic material for high-torque valve stems.
- Rp0.2 · MPa
- ≥ 520
- Rm · MPa
- 800–950
- TEMPERATURE
- −29 … +300 °C
- COST
Chemical composition
Mechanical properties
| STANDARD · CONDITION | Rp0.2 MPa | Rp1.0 MPa | Rm MPa | A % | KV J |
|---|---|---|---|---|---|
| EN 10088-3 · solution annealed (HB ≤ 360) | — | — | ≤ 1200 | — | — |
| EN 10088-3 · P800 | 520 | — | 800–950 | 18 | — |
| EN 10088-3 · P930 | 720 | — | 930–1100 | 16 | — |
Room temperature, bar t ≤ 100 mm. P800 / P930: aged conditions.
Service temperature
The precipitation-hardened structure embrittles over time above ~300 °C. A trim (stem) material.
This is the limit of the material itself. A valve's service temperature is usually set by the seal and seat materials; product pages give it for each seal option.
Physical properties and heat treatment
- DENSITY
- 7.8 kg/dm³
- MODULUS OF ELASTICITY (20 °C)
- 200 GPa
- THERMAL EXPANSION (20–100 °C)
- 10.9 × 10⁻⁶ /K
- THERMAL CONDUCTIVITY (20 °C)
- 16 W/m·K
- SPECIFIC HEAT (20 °C)
- 500 J/kg·K
- ELECTRICAL RESISTIVITY
- 0.71 µΩ·m
- MAGNETISM
- magnetic
- HEAT TREATMENT
- Solution annealing, followed by ageing to the required strength (P800 … P1070).
Media suitability GENERAL TREND
Emsal assessment. The final choice is made from corrosion tables, taking concentration, temperature, chloride content and flow velocity into account.
Strengths and weaknesses
Strengths
- One of the highest strengths among stainless steels
- Markedly better corrosion resistance than martensitic grades
- Low distortion in heat treatment
Weaknesses
- Risk of stress corrosion in chlorides and H₂S (depends on the aged condition)
- Brittleness if incorrectly aged
- Not suitable for welded joints
Manufacturing and use
- ECONOMY
- Medium to high.
- MANUFACTURING METHODS
- Turning from bar + ageing
- TYPICAL VALVE PARTS
- Stem (high torque) · Pin · Spring
Used in 1 Emsal product
Source: EN 10088-3. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.