1. Material Definition and Core Properties
07Cr25Ni21 (equivalent to US grade 310S) is an ultra-high-temperature austenitic stainless steel designed for extreme oxidizing environments. Its composition features:
High chromium nickel base (Cr 24.0-26.0%, Ni 19.0-22.0%): Provides excellent oxidation resistance, allowing continuous use at 1150°C;
Ultra-low carbon (C ≤ 0.08%): Completely prevents intergranular corrosion caused by carbide precipitation;
Purity control: Phosphorus ≤ 0.045%, Sulfur ≤ 0.030%, Nitrogen ≤ 0.11%.
Implementation standards: ASTM A312/A358 (American Standard), GB/T 14976 (Chinese Standard).
2. Performance Advantages and Limiting Parameters
High-Temperature Oxidation Resistance:
Maximum continuous operating temperature 1150°C, short-term resistance 1200°C;
Oxidation resistance over five times that of 304 stainless steel;
Corrosion Resistance:
Resistant to nitric acid, molten alkali, and sulfiding environments (such as petrochemical cracking furnaces);
Passes ASTM A262 Practice E intergranular corrosion testing;
Mechanical Properties:
Room-temperature tensile strength ≥515 MPa, elongation ≥40%;
High-temperature strength maintained at 800°C ≥80 MPa.
3. Typical Applications
Industrial Furnaces:
Radiant tubes for heat treatment furnaces and heat-resistant components for roller hearth kilns;
Inner linings for secondary combustion chambers in waste incinerators;
Energy Equipment:
High-temperature piping in coal chemical gasifiers;
Receiver tubes for solar thermal power generation;
Special Applications:
Insulation support components for aerospace engine tail nozzles;
Nuclear power spent fuel reprocessing equipment. 4. Comparison with Similar Materials
vs. 06Cr25Ni20 (low-carbon version of 310S):
Slightly higher carbon content, 10% higher high-temperature strength;
5-8% lower cost, but slightly inferior weldability;
vs. Inconel 601:
Lower nickel content, half the cost;
Comparable performance in a purely oxidizing environment.
5. Processing and Procurement Key Points
Key Processes:
Welding requires ER310 wire, preheating temperature 150-200°C;
Solution treatment (rapid cooling at 1050-1100°C) is required after hot forming;
Testing Requirements:
100% penetrant testing (PT) to detect surface cracks;
High-temperature tensile testing (800°C for verification);
