What are Alloy 825 and Alloy 925?
Alloy 825 (Incoloy 825, UNS N08825)：
Alloy 825 (UNS N08825 / Incoloy®825) is a titanium‑stabilized austenitic nickel‑iron‑chromium alloy. Added molybdenum and copper grant outstanding anti‑corrosion performance. Widely supplied as round bar, it resists oxidizing & reducing acids and chloride‑induced stress corrosion for chemical and sour‑service projects.
Alloy 925 (Incoloy 925, UNS N09925)：
Alloy 925 (UNS N09925 / Incoloy®925) is age‑hardenable nickel‑iron‑chromium alloy with Mo, Cu, Ti and Al. As high‑strength nickel‑alloy round bar, it delivers superior mechanical properties while maintaining good corrosion resistance for demanding oil‑gas sour‑gas working conditions processes.
Now that you know the basic differences between Alloy 825 and Alloy 925, you may still be unsure which grade matches your working environment. Send us your specifications for a free professional grade evaluation.
Alloy 825 vs Alloy 925：Comparison of Chemical Elements
| Element | Incoloy 825 (N08825) | Incoloy 925 (N09925) | Difference Note |
|---|---|---|---|
| Ni | 38.0‑46.0% | 38.0‑46.0% | Same composition range |
| Cr | 19.5‑23.5% | 19.5‑22.5% | Identical; provides oxidation & acid corrosion resistance |
| Fe | ≥22% (balance) | ≥22% (balance) | Identical |
| Mo | 2.5‑3.5% | 2.5‑3.5% | Identical; PREN≈35‑38 |
| Cu | 1.5‑3.0% | 1.5‑3.0% | Identical; improves resistance to dilute sulfuric acid |
| Ti | 0.6‑1.2% | 1.8‑2.4% | Higher Ti for γ' (Ni₃Ti/Al) age‑hardening precipitation |
| Al | ≤0.20% | 0.10‑0.50% | 825 contains negligible Al; Al added in 925 to assist γ' formation |
| C | ≤0.05% | ≤0.03% | Tighter carbon limit for 925 (prevent age‑related sensitization) |
| Mn / Si / S | ≤1.0 / ≤0.5 / ≤0.015 | ≤1.0 / ≤0.5 / ≤0.010 | Stricter sulfur limit for 925 (improves SSC resistance) |
Key Difference: Ti‑Al Alloying and Carbon Control
Analysis：
- Alloy 925(Incoloy 925) incorporates titanium and aluminium for precipitation hardening, which greatly elevates tensile strength and yield strength. It retains comparable corrosion resistance to Incoloy 825 while achieving much higher mechanical properties via age‑hardening heat treatment.
- Alloy 825(Incoloy 825)is optimised for general‑purpose corrosion resistance, performing well in acidic media and chloride‑rich environments. It is titanium‑stabilised but non‑age‑hardenable, so its tensile and yield strength remain at relatively low levels even after solution annealing.
Alloy 825 vs Alloy 925：Comparison of Mechanical Properties
| Property | Alloy 925 (Incoloy 925, UNS N09925) | Alloy 825 (Incoloy 825, UNS N08825) | Notes |
|---|---|---|---|
| Solution Annealed Tensile Strength | ≥ 685 MPa | 515‑690 MPa | 925 is stronger |
| Yield Strength | ≥ 271 MPa | 205‑275 MPa | 925 is better for high‑load applications |
| Aged Tensile Strength | ≥ 1154 MPa | ‑ | Precipitation hardening exclusive to 925 |
| Hardness | HRB 76 (annealed) | HRB 70‑80 | 925 slightly harder |
| Elongation | 56 % | 30‑50 % | 925 retains ductility after aging |
Conclusion：
- Alloy 925(Incoloy 925) is the preferred selection for high‑stress, high‑pressure sour‑service environments, typical for oil & gas downhole components. Its age‑hardened high strength is paired with corrosion resistance comparable to Incoloy 825.
- Alloy 825(Incoloy 825) is well‑suited for general chemical processing and seawater‑exposed service. It delivers reliable corrosion protection for applications without demanding high‑strength mechanical requirements.
Alloy 825 vs Alloy 925: Differences in Heat Treatment and Microstructure
| Item | Alloy 825 (Incoloy 825, UNS N08825) | Alloy 925 (Incoloy 925, UNS N09925) |
|---|---|---|
| Solution Annealing | 940–980 °C, water quenched after holding (the only mandatory heat treatment) | 900–980 °C, water quenched after holding → Soft condition (for easy machining) |
| Age Hardening | ✖ None (no age hardening, no strengthening precipitates) | ✔ Mandatory: 620–720 °C × 8–16h, air/furnace cooled → Dispersed precipitation of γ'(Ni₃(Ti,Al)) |
| Delivery Condition | Solution Annealed (SA) | Solution Treated (for machining) or Solution Treated + Aged (for final assembly) |
| Microstructure | Single-phase austenite + TiC/TiN inclusions | Austenite + TiC/TiN + γ' precipitates (after age hardening) |
Alloy 825(Incoloy 825)
Alloy 825 adopts only solution‑annealing heat treatment. Its microstructure is fully austenitic matrix stabilized by titanium. No precipitation‑hardening response occurs; grain size is controlled by annealing temperature, without age‑hardened precipitates formed after cooling.
Alloy 925(Incoloy 925)
Alloy 925 requires solution annealing followed by age‑hardening. Its austenitic matrix disperses fine Ti‑Al‑Ni precipitates after aging treatment. These nano‑scale precipitates block dislocation movement and greatly boost tensile and yield strength of the alloy.
Vertical Rapid Solution Quench Furnace
Alloy 825 vs Alloy 925：Comparison of Corrosion Resistance
| Environment | Incoloy 825 | Incoloy 925 |
|---|---|---|
| CO₂ Corrosion (Sweet Corr., ≤150°C) | ★★★★☆ | ★★★★☆ |
| Trace H₂S (NACE MR0175 Limited p_H₂S) | SSC Resistant (Annealed Condition) | SSC Resistant + High Strength (110ksi Class) |
| Cl⁻ SCC (Aqueous Solution) | ★★★★★ (Fully Austenitic) | ★★★★★ (Fully Austenitic) |
| Pitting / Crevice Corrosion (PREN≈35-38) | ★★★★ | ★★★★ |
| Dilute Sulfuric Acid / Phosphoric Acid (Mixed Oxidizing + Reducing) | ★★★★ | ★★★★ |
| Strong Reducing Acids (Concentrated HCl / HF) | ✖ Not Applicable | ✖ Not Applicable |
| High-Temperature Oxidation / Carburization (>650°C, Pressure-Bearing) | Up to ~540-590°C for Process Equipment | Not Designed for This Application |
Alloy 825 (Incoloy 825, UNS N08825)：
It delivers reliable resistance to chloride‑induced corrosion, seawater, dilute sulfuric and phosphoric acid. Without precipitation hardening, its SSC performance is moderate; it suits general corrosive chemical service, not high‑stress sour‑gas working conditions.
Alloy 925 (Incoloy 925, UNS N09925)：
With higher Ni‑Mo content plus age‑hardened microstructure, it offers superior SSC resistance. It performs well in seawater, chloride media and acidic environments, fit for high‑stress sour‑oil‑gas field demanding both strength and corrosion resistance.
Corrosion resistance varies greatly depending on alloy composition and heat treatment. If you are confused about which material performs better in your acid, chloride, or sour gas environment, submit your working medium for accurate material recommendation.
Application Differences: Alloy 825 vs Alloy 925
Application Scenarios of Alloy 825
Focus on Corrosion Resistance & Conventional Load‑Bearing
- Chemical & Acid‑making: Resists dilute strong acids, alkalis and chlorides. Used for heat exchangers, pickling hardware, reactors, valves and pumps for general‑strength corrosion‑resistant parts.
- Marine & Seawater Treatment: For seawater and brine service: seawater‑cooled heat exchangers, desalination units and offshore cooling piping. Optimized against seawater corrosion; not for high‑stress sour downhole conditions.
- General Oil‑Gas & Environmental: For hydrocarbon recovery, flue‑gas treatment, food and pharmaceutical processing. Fits equipment from cryogenic to moderate‑temperature ranges.
Application Scenarios of Alloy 925
Focus on High‑Strength & Severe Corrosive Service
- Sour Downhole & Wellhead Hardware: For H₂S‑CO₂‑Cl⁻ sour fields. Applied to tubing strings, hangers, safety valves and couplings. Rated for 100‑150 MPa under cyclic tension‑compression and sour‑media corrosion.
- High‑load Marine Components: Pump shafts, propeller shafts, high‑strength fasteners. Combines resistance to seawater corrosion, galvanic corrosion and cyclic bending stress.
- Petrochemical High‑load Parts: High‑pressure flange bolts, shafts and pipeline connectors for long‑term high‑preload service in complex corrosive media. Rarely used for pressure‑vessel shell base material.
Alloy 825 vs Alloy 925: Cost‑Benefit Analysis
Alloy 825 vs Alloy 925 Price Comparison：
| Item | Alloy 825 (UNS N08825) | Alloy 925 (UNS N09925) | Price Difference Explanation |
|---|---|---|---|
| Delivery Condition | Solution Annealed | Age Hardened (AH Condition) | Alloy 925 requires additional solution treatment and precipitation aging, increasing manufacturing costs. |
| Indicative FOB Price (USD/kg) | 17–24 | 26–35 | Alloy 925 is typically 40–70% more expensive than Alloy 825, depending on product form, quantity and nickel market conditions. |
| Indicative EXW China (RMB/kg) | 180–250 | 280–380 | Domestic prices fluctuate with nickel prices, dimensions and certification requirements. |
| Typical Availability | Widely Available (Stock for Common Sizes) | Limited Stock, Mostly Made to Order | Alloy 925 has much lower global production volume than Alloy 825. |
| Typical Lead Time | Stock or 2–4 Weeks | Usually 6–10 Weeks | Alloy 925 requires additional heat treatment and production scheduling. |
| Inspection & Certification | EN10204 3.1, PMI on Request | EN10204 3.1, PMI, Hardness Verification, NACE MR0175 / ISO 15156 (when specified) | Oil & gas projects often require more comprehensive inspection documentation for Alloy 925. |
| Small Quantity Premium | +15%–25% | +25%–40% | Alloy 925 has higher setup and heat-treatment costs, making small orders proportionally more expensive. |
| Main Cost Drivers | Nickel, Molybdenum, Copper | Nickel, Molybdenum, Titanium, Age-Hardening Process | Titanium addition and precipitation-hardening significantly increase production costs. |
The prices above are for reference only and are intended to assist buyers with preliminary budgeting. Actual quotations vary depending on nickel market prices, product form (plate, bar, pipe or forging), dimensions, quantity, heat treatment condition, inspection requirements, machining services and delivery schedule. Please contact GNEE STEEL for the latest quotation and stock availability.
Core Advantages of Alloy 825: Why It Delivers Better Cost‑Effectiveness?
1. No costly heat treatment required Alloy 825 is directly used in the solution-annealed state without precipitation hardening. Alloy 925 needs extra aging treatment for high strength. This saves substantial time and processing costs, especially for large and mass-produced components.
2. Excellent machinability and formability With superior ductility and plasticity, Alloy 825 supports conventional cold bending, deep drawing and welding. Aged Alloy 925 features ultra-high strength, causing severe tool wear, difficult machining and higher manufacturing costs.
3. Anti-sensitization after welding for efficient construction Benefiting from Ti stabilization (Ti/C=8–12) and low-carbon design, Alloy 825 avoids chromium carbide precipitation. It maintains intergranular corrosion resistance without post-weld heat treatment, greatly simplifying on-site construction.
4. Fully competent corrosion resistance for most working conditions Alloy 825 matches Alloy 925 in corrosion performance, with SCC immunity, excellent pitting/crevice corrosion resistance and good acid tolerance. It meets NACE MR0175 standards, making it a cost-effective alternative without extra strength redundancy.
Alloy 825 vs Alloy 925：Material Selection Decision Summary
✅ Select Incoloy 825 (N08825)
- Chemical / Petrochemical process equipment: H₂SO₄ / H₃PO₄ heat exchangers, absorption towers, piping, tank linings.
- Seawater coolers (flowing‑seawater service, no high tensile load; evaluate crevice‑corrosion risk for stagnant / crevice conditions).
- Flue‑gas desulfurization (FGD) components.
- Non‑loaded or low‑stress acid‑resistant vessels, pipelines and lining components.
✅ Select Incoloy 925 (N09925)
- Oil & gas well‑completion: API 110‑ksi casing/tubing subs, packer mandrels, downhole safety valve stems, pump shafts.
- Service within NACE MR0175 / ISO 15156‑3 operating envelope with CO₂ + H₂S; requires combined SSC resistance and high yield strength.
- High‑strength Cl⁻‑SCC‑resistant fasteners for offshore platforms (avoid long‑term full immersion and crevice‑corrosion‑dominated conditions).
❌ Scenarios Not Recommended for Incoloy 925
Large process vessels (high cost, excessive strength margin wasted); shell sections of large strong‑acid storage tanks (Alloy 825 delivers better overall cost‑performance; full age‑hardened mechanical properties are hard to restore after welding large 925 shells); high‑temperature cracking / reformer furnace tubes (800HT series is preferred).
Choosing between Alloy 825 and 925 depends on stress level, corrosion medium, and industry standards (NACE MR0175). If you still hesitate, send your project parameters, and our nickel alloy engineers will complete your final material selection.
Why Choose GNEE STEEL as Your Incoloy 825 Supplier?
Spot Inventory
GNEE maintains ready‑to‑ship Incoloy 825 stock covering bar, plate, pipe and forging blanks in UNS N08825 / 2.4858. We keep frequently‑used sizes in warehouse to shorten lead‑time for urgent chemical, offshore and FGD project orders
Material Certifications
All Incoloy 825 deliveries come with EN 10204 3.1 /3.2 mill test reports complying with ASTM B424, B425, B409. NACE MR0175 documentation is available for sour‑gas applications with full heat‑lot traceability
Processing & Cutting Services
We perform saw cutting, plasma cutting, turning, grinding, solution annealing and pickling for Incoloy 825. Hard‑to‑machine nickel alloy is handled with dedicated tooling to control dimensional tolerance and surface finish for different product forms.
Quality Inspection
Each batch runs XRF spectral analysis, tensile‑hardness mechanical test, ultrasonic testing (UT) and visual inspection. We verify chemical composition, mechanical properties and internal defects before Incoloy 825 goods leave our workshop
Packaging & Shipping
Incoloy 825 adopts anti‑rust paper wrapping, wooden crate or steel frame packaging to avoid scratch and seawater corrosion during ocean freight. Markings include heat number, UNS grade, dimension for customs clearance and receiving identificationGnee Steel...
Export & Delivery Experience
Decades‑long nickel‑alloy export experience covers full document preparation, container loading and pre‑shipment check. We are familiar with special alloy customs requirements for chemical, oil‑gas and marine end‑users worldwide
Quality Inspection
Material Certifications
Packaging & Shipping
Whether you need standard Alloy 825 for general corrosion resistance or high-strength Alloy 925 for sour oilfield service, GNEE STEEL provides full-spec materials, complete certifications, and strict quality testing. Send your inquiry now for the latest factory price.
FAQ:
What is the difference between INCOLOY 825 and ss316l?
Incoloy 825 is ideal for aggressive and highly corrosive environments, high-temperature applications, or resistance to stress corrosion cracking is essential. On the other hand, SS316 is ideal for applications requiring good resistance to general corrosion and pitting corrosion.
Is Inconel 825 the same as alloy 825?
Incoloy 825 alos known as Inconel 825. Its is an alloy formulated of Nickel, Chromium and Iron with extension of Molybdenum, Copper and Titanium. The alloy 825 invented to contribute exceptional resistance to many corrosive environments and reducing environments that acquire sulphuric acid and phosphoric acid.
What is the difference between INCOLOY 800 and 825?
Incoloy 800 offers reliable high-temperature stability at a lower cost, making it suitable for applications where corrosion risk remains moderate. Incoloy 825, with its superior resistance to acids and chlorides, becomes the preferred choice for harsh chemical environments, even if it means a higher upfront expense.
Does Inconel 825 rust?
The outstanding attribute of INCOLOY alloy 825 is its high level of corrosion resistance. In both reducing and oxidize environments, the alloy resists general corrosion, pitting, crevice corrosion, intergranular corrosion, and stress-corrosion cracking.
