Alloy 825 UNS N08825: Premium Industrial Austenitic Nickel-Iron-Chromium Alloy with Superior Corrosion Resistance
Alloy 825 UNS N08825: Premium Industrial Austenitic Nickel-Iron-Chromium Alloy with Superior Corrosion Resistance
Alloy 825 (commercially known as Incoloy® 825, UNS N08825, W.Nr. 2.4858, Chinese Grade NS142(GB/T standard)) is a globally recognized titanium-stabilized austenitic nickel-iron-chromium alloy extensively adopted for industrial corrosive service conditions, highly trusted by manufacturers of chemical equipment, oil & gas extraction facilities, marine engineering installations, flue gas desulfurization systems and nuclear power equipment. Formulated with a precisely balanced multi-element system of nickel, chromium, molybdenum, copper and titanium, this alloy features comprehensive resistance to complex acid and alkali corrosion, excellent tolerance to chloride-induced material failure, and stable mechanical properties at moderate elevated temperatures. It boasts superior formability and full compatibility with mainstream welding procedures, serving as the core specialized material for engineering projects operating under diversified severe corrosive environments. Developed specifically…
Alloy 825 (commercially known as Incoloy® 825, UNS N08825, W.Nr. 2.4858, Chinese Grade NS142(GB/T standard)) is a globally recognized titanium-stabilized austenitic nickel-iron-chromium alloy extensively adopted for industrial corrosive service conditions, highly trusted by manufacturers of chemical equipment, oil & gas extraction facilities, marine engineering installations, flue gas desulfurization systems and nuclear power equipment. Formulated with a precisely balanced multi-element system of nickel, chromium, molybdenum, copper and titanium, this alloy features comprehensive resistance to complex acid and alkali corrosion, excellent tolerance to chloride-induced material failure, and stable mechanical properties at moderate elevated temperatures. It boasts superior formability and full compatibility with mainstream welding procedures, serving as the core specialized material for engineering projects operating under diversified severe corrosive environments.
Developed specifically for service in mixed oxidizing and reducing corrosive media, Alloy 825 sustains long-term reliable performance in dilute sulfuric acid, phosphoric acid, nitric acid, organic acids, strong caustic solutions, seawater salt spray and hydrogen sulfide-containing oil & gas media. Titanium stabilization drastically mitigates susceptibility to intergranular corrosion after welding, eliminating mandatory post-weld solution heat treatment while preserving full anti-corrosion capacity. This characteristic optimizes production efficiency and long-term operational reliability for process equipment, making the alloy ideal for corrosion-resistant piping, heat exchanger tube bundles, reaction vessels, internal FGD components and downhole corrosion-resistant structural parts.
Multi-purpose anti-corrosion alloy for moderate-temperature, high-pressure corrosive working conditions
Maximum Continuous Service Temperature
538℃ (1000°F)
Alloy 825 UNS N08825 Chemical Composition (Mass %)
Note: Ranges below comply with ASTM/ASME standards. Final delivered chemical composition shall be subject to factory Mill Test Certificates (MTC) and third-party inspection reports.
Element
Alloy 825 UNS N08825
Nickel (Ni)
38.0–46.0
Chromium (Cr)
19.5–23.5
Iron (Fe)
Balance, min. 22.0
Molybdenum (Mo)
2.5–3.5
Copper (Cu)
1.5–3.0
Titanium (Ti)
0.60–1.20
Carbon (C)
Max. 0.05
Manganese (Mn)
Max. 1.00
Silicon (Si)
Max. 0.50
Sulfur (S)
Max. 0.030
Phosphorus (P)
Max. 0.030
Aluminum (Al)
Max. 0.20
Applicable Industrial Standards
Product Form
Applicable Specifications
Seamless Heat Exchanger Tubes
ASTM B423 / ASME SB423
Plates, Sheets & Strips
ASTM B424 / ASME SB424
Hot Rolled & Forged Bars
ASTM B425 / ASME SB425
Forgings, Fittings & Flanges
ASTM B564 / ASME SB564
Sour Service Oil & Gas Equipment
NACE MR0175, API 5CRA
Pressure Vessel Construction
ASME Section VIII Boiler & Pressure Vessel Code
Compliant with NACE MR0175 / ISO 15156 for sour oil & gas service under specified hardness limits
Incoloy® 825 Core Performance Advantages
Performance Item
Technical Description
Universal Acid & Alkali Corrosion Resistance
Chromium provides oxidation resistance; molybdenum and copper synergistically withstand reducing acids including sulfuric acid and phosphoric acid, delivers very low uniform corrosion rates under alternating oxidizing and reducing acid-alkali exposure
Chloride Corrosion Resistance
High nickel matrix effectively inhibits chloride-induced stress corrosion cracking; molybdenum enhances resistance to pitting and crevice corrosion, suitable for seawater and salt spray environments
Intergranular Corrosion Resistance
Titanium stabilization restricts chromium carbide precipitation during welding; the alloy retains full corrosion resistance even after exposure to sensitization temperature ranges
Moderate-Temperature Microstructure Stability
Negligible grain coarsening and minimal degradation of mechanical & anti-corrosion properties under long-term thermal cycling up to 538°C (1000°F)
Hot & Cold Formability & Weldability
Excellent ductility with minimum elongation of 30%, compatible with bending, stamping and forging processes. Suitable for GTAW, GMAW and SMAW with matching filler metals; Post-weld heat treatment is generally unnecessary for standard service; solution annealing (940–980°C) is optional for heavy-wall components or highly corrosive sour service to restore full intergranular corrosion resistance
Low-Temperature Toughness
Free from low-temperature brittleness, Retains stable impact toughness down to -196°C (liquid nitrogen temperature), free from cryogenic brittleness for low-temperature corrosion-resistant equipment
UNS N08825 Typical Industrial Applications
Industry Sector
Representative Components
Oil & Gas Exploration & Production
Sour crude & gas transmission pipelines, downhole corrosion-resistant tools, service valves, heat exchanger tube bundles
Alternating acid-alkali service, general chloride salt spray corrosive environments
Alloy 825 UNS N08825
Balanced multi-alloy element formulation delivers consistent corrosion resistance in both oxidizing and reducing media with universal applicability
Long-term service in seawater, brine and high-chloride environments
Alloy 825 UNS N08825
High molybdenum & nickel composition eliminates risks of pitting, crevice corrosion and stress corrosion cracking
Sour oil & gas, high-temperature acidic flue gas pressure-bearing service
Alloy 825 UNS N08825
Compliant with NACE standards for sour media, excellent sulfide corrosion resistance and stable pressure-bearing performance up to 550°C
Heavy welding fabrication with impractical post-weld heat treatment procedures
Alloy 825 UNS N08825
Titanium-stabilized metallurgy eliminates intergranular corrosion risks after welding, simplifying post-processing and lowering production costs
C&N Product Supply Scope & Packaging Standards
Item
Standard Supply Package
Available Product Range
Hot/cold rolled plates, coils, seamless tubes, welded pipes, forged fittings, flanges, round bars, open die forgings, wire rods
Packaging Solutions
Sealed moisture-proof plastic wrapping, steel band reinforcement, export fumigated wooden cases, standard pallet packaging
Product Marking
Alloy grade UNS N08825, dimensional specifications, heat lot number, production batch, theoretical net weight, stamped material identification
Accompanying Documentation
Complete original Mill Test Certificates, third-party physical & chemical inspection reports, spectral & NDT inspection records-NDT includes UT (ultrasonic testing for internal defects) and PT (liquid penetrant testing for surface flaws), full product traceability files
Alloy 825 (UNS N08825) is a standardized austenitic nickel-iron-chromium alloy engineered for complex corrosive industrial environments. Its integrated nickel-chromium-molybdenum-copper-titanium alloy matrix delivers long-term protection against oxidizing/reducing acids, alkalis, chlorides and sulfide corrosive media, paired with stable moderate-temperature performance and excellent fabrication & welding compatibility. It serves as a reliable material solution for corrosion-critical equipment across chemical, oil & gas, marine, FGD and nuclear power industries. C&N provide custom machining for non-standard dimensions, and all Alloy 825 deliveries are supported by full authoritative inspection documentation to meet acceptance criteria for domestic and international pressure vessel, oil & gas and nuclear power projects. contact us for a quote today.
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