1. What is EN 10297 X1NCrMoCu25-20-5?
Answer:
EN 10297 X1NCrMoCu25-20-5 is a super austenitic stainless steel seamless tube standardized under EN 10297, renowned for its exceptional corrosion resistance in aggressive environments.
Key Composition: 25% Ni, 20% Cr, 5% Mo, and 1.5% Cu.
Equivalent Grades: UNS N08904 (904L), DIN 1.4539.
Key Feature: Outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC), with a PREN (Pitting Resistance Equivalent Number) >35.
2. What are the mechanical properties?
Answer (annealed condition):
Tensile Strength: 490–690 MPa
Yield Strength (0.2% offset): ≥220 MPa
Elongation: ≥35%
Hardness: ≤200 HB
Note: The high nickel and molybdenum content ensures stability in both acidic and chloride-rich environments.
3. How does it compare to standard 316L (X2CrNiMo17-12-2)?
Answer:
Superior Corrosion Resistance: Higher Ni (25% vs. 12%) and Mo (5% vs. 2.5%) make it ideal for sulfuric acid, phosphoric acid, and seawater applications.
Copper Advantage: Cu (1.5%) enhances resistance to reducing acids (e.g., sulfuric acid at low concentrations).
Cost: Significantly more expensive but justified for critical industrial use.
4. What are the fabrication guidelines?
Answer:
Welding: Use TIG/PAW with matching fillers (e.g., ER385 or ERNiCrMo-10). Maintain low heat input to avoid σ-phase precipitation.
Machining: High work-hardening rate requires sharp carbide tools and slow speeds.
Heat Treatment: Solution anneal at 1100–1150°C followed by rapid cooling to optimize corrosion resistance.
5. Where is this grade commonly applied?
Answer:
Chemical Industry: Reactors, piping for sulfuric/phosphoric acid production.
Oil & Gas: Offshore platforms, subsea equipment (resists H₂S and chlorides).
Desalination: Heat exchangers and brine piping.
Pharmaceutical: Sterilizable equipment requiring ultra-clean surfaces.
