1. Material Definition and Core Characteristics
08Cr18Ni11NbFG is a niobium-stabilized austenitic stainless steel pipe specifically designed for nuclear power plants ("FG" stands for nuclear-grade material). Its composition and standard features are as follows:
Optimized composition:
Chromium-nickel base (Cr 17.0-19.0%, Ni 10.0-12.0%) + niobium (Nb ≥ 10 × C%, typically 0.30-0.70%);
Ultra-low carbon (C ≤ 0.08%), controlled phosphorus and sulfur limits (P ≤ 0.025%, S ≤ 0.010%);
Nuclear-grade standard: Complies with RCC-M M3301 (French standard) or GB/T 5310 Appendix F (Chinese nuclear grade). An irradiation performance report is required.
2. Performance Advantages and Special Requirements
Intergranular Corrosion Resistance: Passes ISO 3651-2 test (sulfuric acid + copper sulfate + copper chips);
Irradiation Stability: Elongation maintained at ≥25% at a fast neutron dose of 1×10²¹n/cm²;
Processing Characteristics:
Welding requires ER347Nb wire, and post-weld pickling and passivation are required;
Solution treatment temperature: 1050-1100°C (requires argon shielding and cooling).
3. Typical Nuclear Power Plant Applications
Primary Auxiliary Systems:
Chemical Volume Control System (CVCS) piping;
Residual Heat Removal System (RHR) heat exchanger tubes;
Safety-Level Equipment:
Containment Spray System piping;
Emergency Core Cooling System (ECCS) manifolds. 4. Comparison with Ordinary 347 Steel
vs. 07Cr18Ni11Nb:
The "FG" version offers higher purity ([O] ≤ 15ppm, [H] ≤ 1ppm);
Adds irradiation performance testing, resulting in a 20-30% higher cost;
vs. Z2CND18-12N (French Nuclear Grade):
Higher niobium content, resulting in a 10% increase in high-temperature strength;
Advantages of Domestic Production (60% shorter lead time).
5. Procurement and Testing Key Points
Key Certificates: Material certificates approved by the Nuclear Safety Administration (NNSA) are required;
Special Testing:
100% eddy current and ultrasonic testing (compliant with NB/T 20005.3);
Combined intergranular corrosion and radiation embrittlement testing;
