1. What is EN 10297 X2CrNiMoN17-13-5?
Answer:
EN 10297 X2CrNiMoN17-13-5 is a high-molybdenum, nitrogen-alloyed austenitic stainless steel seamless tube under the European standard EN 10297. It is designed for extreme corrosion resistance, especially in chloride and acidic environments.
Key Composition: 17% Cr, 13% Ni, 5% Mo, and nitrogen (N) for enhanced strength and pitting resistance.
Equivalent Grades: Similar to UNS S31726 or DIN 1.4439 (super austenitic steel).
Key Feature: Exceptionally high PREN (Pitting Resistance Equivalent Number) >40, making it suitable for aggressive media.
2. What are the mechanical properties?
Answer (annealed condition):
Tensile Strength: 650–850 MPa
Yield Strength (0.2% offset): ≥300 MPa (higher than standard 316L due to N and Mo)
Elongation: ≥35%
Hardness: ≤230 HB
Note: Nitrogen and molybdenum synergistically improve strength and localized corrosion resistance.
3. How does it compare to X2CrNiMoN17-13-3 (316LN)?
Answer:
Molybdenum Content: 5% Mo (vs. 3% in 316LN) significantly boosts resistance to sulfuric/phosphoric acids and chloride-induced stress corrosion cracking.
Cost: Higher due to alloy content, but justified for critical applications like chemical processing.
Weldability: Requires low-heat-input methods (e.g., TIG with ER317L filler) to avoid σ-phase formation.
4. What are critical fabrication guidelines?
Answer:
Welding: Use matching fillers (e.g., ER317L or ERNiCrMo-3) and avoid interpass temperatures >150°C.
Machining: High work-hardening rate demands 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 primarily used?
Answer:
Chemical Industry: Reactors for sulfuric acid, bleach, and phosphoric acid production.
Oil & Gas: Downhole equipment in sour (H₂S-rich) environments.
Desalination: Seawater piping and heat exchangers.
Pharmaceutical: Equipment requiring ultra-clean surfaces and sterilization.
