X1NiCrMoCu25-20-5
Super austenitic stainless steel with high nickel, molybdenum and copper. Used in sulphuric and phosphoric acid and in chloride environments where 316L is not enough.
- Rp0.2 · MPa
- ≥ 220
- Rm · MPa
- 520–720
- TEMPERATURE
- −196 … +371 °C
- COST
Chemical composition
Mechanical properties
| STANDARD · CONDITION | Rp0.2 MPa | Rp1.0 MPa | Rm MPa | A % | KV J |
|---|---|---|---|---|---|
| EN 10088-2 · hot-rolled plate (P) | 220 | 260 | 520–720 | 35 | 60 |
| ASTM · 904L (N08904) | 220 | — | ≥ 490 | 35 | — |
Room temperature, solution annealed. EN: Rm 520–720; A transverse 30, longitudinal 35. KV ≥ 60 J (+20 °C and −196 °C, transverse).
Minimum Rp0.2 at elevated temperature
| EN · TEMPERATURE | 20 °C | 100 °C | 200 °C | 400 °C |
|---|---|---|---|---|
| Rp0.2 MPa | 220 | 205 | 175 | 125 |
EN 10028-7 / EN 10088 values; the minimum proof strength used in pressure equipment design.
Service temperature
Not used below −196 °C (EN). Upper limit 371 °C (700 °F).
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
- 8.0 kg/dm³
- MODULUS OF ELASTICITY (20 °C)
- 195 GPa
- THERMAL EXPANSION (20–100 °C)
- 15.8 × 10⁻⁶ /K
- THERMAL CONDUCTIVITY (20 °C)
- 12 W/m·K
- SPECIFIC HEAT (20 °C)
- 450 J/kg·K
- ELECTRICAL RESISTIVITY
- 1.00 µΩ·m
- MAGNETISM
- non-magnetic (solution annealed)
- CRITICAL PITTING TEMPERATURE, CPT (TYPICAL)
- 62 ± 3 °C
- HEAT TREATMENT
- Solution annealing 1100 ± 40 °C, rapid cooling.
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
- Very good resistance among stainless steels in sulphuric and phosphoric acid
- High nickel: resistant to chloride stress corrosion cracking
- CPT ≈ 62 °C: three times that of 316L
Weaknesses
- Falls behind super duplex and 6Mo grades in seawater
- High nickel: expensive and volatile in price
- Half the proof strength of duplex grades
Manufacturing and use
- ECONOMY
- High; about 2–3 times the price of 316L.
- MANUFACTURING METHODS
- Machining from plate and bar · Welded construction
- TYPICAL VALVE PARTS
- Body · Disc · Stem (acid service)
Source: EN 10088-2 / -3. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.