1. Material Definition and Composition Characteristics
07Cr18Ni11Nb is a niobium-stabilized austenitic stainless steel (equivalent to US grade 347). Its core composition is designed as follows:
Chromium-nickel base (Cr 17.0-19.0%, Ni 9.0-12.0%): Ensures basic corrosion resistance;
Niobium-strengthened (Nb ≥ 10 × C%, typically 0.30-0.60%): Stabilizes carbon by forming NbC, completely eliminating the risk of sensitization;
Ultra-low carbon (C ≤ 0.08%), controlled phosphorus and sulfur (P ≤ 0.045%, S ≤ 0.030%).
Implementation standards: GB/T 14976 (National Standard), ASTM A312 (American Standard), EN 10216-5 (European Standard).
2. Core Performance Advantages
Intergranular Corrosion Resistance: Passes ASTM A262 Practice E testing (nitric acid + fluoride environment);
High-Temperature Performance:
Continuous operating temperature 850°C (short-term resistance 950°C);
Oxidation resistance superior to 321 steel (oxidation weight gain reduced by 20% at 900°C);
Processing Characteristics:
ER347 welding wire is recommended for welding, requiring no preheating;
Solution treatment is required after cold working (rapid cooling at 1040-1120°C).
3. Typical Applications
Energy and Power:
Nuclear power plant primary circuit auxiliary piping (RCC-M M3301 certified);
Gas turbine waste heat boiler superheater tubes;
Chemical Equipment:
Strong acid reactors (e.g., concentrated nitric acid storage tanks);
High-temperature hydrogen pipelines;
Special Applications:
Thick-walled components (≤50mm) requiring no post-weld heat treatment. 4. Comparison with similar materials
vs 07Cr17Ni11Ti (321):
Niobium has a stronger carbon fixation ability than titanium (NbC is more stable);
High-temperature strength increased by 15% (800℃ working condition);
vs 06Cr18Ni11Nb (347H):
Lower carbon content, better weldability;
Similar cost but slightly narrower applicable temperature range.
5. Quality control and procurement points
Key tests:
Niobium content test (Nb/C ≥ 10);
Intergranular corrosion test (GB/T 4334 or ASTM A262);
Processing precautions:
Hot forming final rolling temperature ≥ 900℃;
Do not mix with carbon steel tools (to prevent iron contamination);
