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Introduction
Alloy 803 (UNS N08803 / ASTM B409 Alloy 803 plate) is a nickel-iron-chromium alloy specifically engineered for elevated temperature service. With higher chromium (25-29%) and nickel (30-37%) contents than Alloy 800H, this EN equivalent Alloy 803 material (EN 1.4876) provides excellent oxidation resistance in air, flue gases and carburizing atmospheres, high temperature strength (tensile ≥655 MPa at room temperature, retaining ≥240 MPa at 800°C), superior creep resistance (operating continuously up to 1100°C), and outstanding thermal stability under cyclic thermal stress. For context, comparable alloys include Alloy 800H (UNS N08810) and Alloy 800HT (UNS N08811) – while Alloy 800H/HT are widely used for general high-temperature service, Alloy 803 delivers superior creep strength and oxidation/corrosion resistance above 815°C, making it the preferred choice for the most demanding thermal environments.
Chemical compotents(%)
Composition | C | Si | Mn | P | S | Cr | Ni | Cu | Ti | Al |
Min | 0.06 | \ | \ | \ | \ | 25 | 32 | \ | 0.15 | 0.15 |
Max | 0.1 | 1 | 1.5 | 0.045 | 0.015 | 29 | 37 | 0.75 | 0.60 | 0.60 |
Mechanical properties
Rigidity | Tensile strength | Yield strength | Elongation |
HRB≤90 | ≥485MPa | ≥170MPa | ≥35% |
Physical properties
Density | Melting points | Specific heat | Magnetism | Resistivity | Thermal conductivity | Linear expansivity |
7.75kg/dm3 | 1350-1400℃ | 0.46J/(Kg.℃） | yes | 0.6Ω·mm²/m(20℃) | :36.9W/(m.k)(100℃) | 10×10-6/K(0-100℃) |
Alloy 803 Stainless Steel Available Products and Standard
1. ASTM B409 / ASME SB409
(Standard Specification for Nickel‑Iron‑Chromium Alloy Plate, Sheet, and Strip)
Type:
Alloy 803 Nickel‑Iron‑Chromium Alloy Plate
Alloy 803 Sheet
Alloy 803 Strip
Size Range:
Sheet / Strip: 0.1 – 6.0 mm thick × 20 – 1500 mm wide
Plate: 3.0 – 100 mm thick × up to 3500 mm wide
Length: up to 12000 mm
Surface: Annealed (solution annealed), Pickled, Bright, Cold‑rolled finish
Testing: Chemical analysis (Ni 32‑37%, Cr 25‑29%, Fe balance, Al 0.15‑0.60%, Ti 0.15‑0.60%), tensile test (Rm ≥655 MPa at RT, Rp0.2 ≥310 MPa), elongation (≥30%), hardness (HBW 85‑120), flattening test (for strip), oxidation resistance test, creep‑rupture test, dimensional inspection
2. ASTM B408 / ASME SB408
(Standard Specification for Nickel‑Iron‑Chromium Alloy Seamless Pipe and Tube)
Type:
Alloy 803 High Temperature Strength Seamless Pipe
UNS N08803 Tube
Size Range:
Seamless pipe OD: 6.0 – 610 mm (1/8″ – 24″ NPS)
Tube OD: 3.0 – 250 mm
Wall thickness: 0.5 – 60 mm
Length: up to 18000 mm
Surface: Annealed, Pickled, Bright, Cold‑drawn as‑rolled
Testing: Chemical analysis, tensile test (Rm ≥655 MPa, Rp0.2 ≥310 MPa), elongation (≥30%), flattening test, flaring test, hydrostatic or NDE test, creep‑rupture test (up to 1093°C), dimensional inspection
Applications
(1)Furnace – Alloy 803 for furnace components (radiant tubes, furnace baskets, trays, conveyor belts, thermocouple protection tubes) provides excellent oxidation and carburization resistance along with high creep strength in continuous high-temperature operation up to 1150°C.
(2)Petrochemical Industry – Alloy 803 for petrochemical industry (ethylene cracking furnace tubes, reformers, ethylene cracking units, catalytic cracking units, sulfur recovery units) withstands severe carburization, metal dusting, and oxidation conditions while maintaining stress rupture strength.
(3)Heat Treatment Equipment – Alloy 803 for heat treatment equipment (retorts, muffles, furnace linings, heating elements, fixturing) leverages its high-temperature strength and resistance to scaling and thermal shock in both air and controlled atmospheres.
(4)Boiler Components – Alloy 803 for boiler components (superheater tubes, reheater tubing, tight and twisted ID finned tubing in petrochemical boilers) provides superior sulfidation resistance and creep rupture strength in fossil fuel and nuclear power generation systems.
(5)High Temperature Equipment – Alloy 803 for high temperature equipment (high-temperature heat exchangers, power piping, gas turbine components) maintains mechanical integrity and resists hot gas corrosion in cyclic service where 800H approaches its oxidation limits.
(6)Thermal Processing – Alloy 803 for thermal processing (heat recovery systems, waste heat recovery units, process tubes, compact heat exchangers for microturbine recuperators) delivers balanced oxidation-sulfidation-carburization resistance combined with excellent thermal fatigue stability.
MONO Group is one of Alloy 803 stainless steel Manufacturer & Supplier & Wholesaler from China, We can supply ASTM / DIN / ISO / GB stndard high quality alloy plate, sheet, round bar, tube, pipes, fittings, flange, pls contact us freely for your RFQ to info@monokj.com
