In the field of high-temperature engineering, assuming all Inconel 625 (UNS N06625) alloys have identical properties could result in millions of dollars in losses. For engineers designing flare towers, aircraft engine piping, or reactor internal structures, creep rupture failure is one of the most challenging problems.
At Gnee Alloy, we eliminate this risk through precision heat treatment. Our Grade 2 Inconel 625 alloy (solution annealed) is specifically designed to withstand the "hazardous zones" of extreme temperatures.
Click here for an Inconel 625 product quote
What is Inconel 625 Grade 2 alloy?
What is Inconel 625 Grade 2 alloy?
Inconel 625 Grade 2 refers to the solution-treated version of the standard Inconel 625 high-temperature alloy. It is a nickel-chromium-molybdenum alloy reinforced with niobium. This alloy possesses high strength and excellent corrosion resistance, and can operate stably at temperatures ranging from low to extreme, making it widely used in the aerospace, marine, chemical, and oil and gas industries.
What is the difference between Inconel 625 Grade 1 and Grade 2?
Inconel 625 Grade 2 products are supplied in the solution-annealed state. The main difference between Grade 1 and Grade 2 lies in the annealing temperature. The minimum annealing temperature for Grade 1 products is 1600°F (871°C), while the minimum annealing temperature for Grade 2 products is 2000°F (1093°C).
1. Inconel 625 Grade 2 Material Overview
| Parameter | Description |
|---|---|
| Material | Inconel 625 Grade 2 |
| UNS Number | N06625 |
| Chinese Equivalent | GH3625 |
| Material Type | Wrought Nickel-based Corrosion Resistant Superalloy |
| Strengthening Mechanism | Solid-solution strengthening (Mo + Nb) |
| Product Forms | Bar, plate, tube, strip, wire |
| Typical Applications | Chemical equipment, marine engineering, aircraft engine components, nuclear industry |
| Maximum Service Temperature (Load-Bearing) | ~600°C |
| Maximum Service Temperature (Oxidation) | ~980°C |
| Delivery Condition | Solution treated (annealed) – not age-hardenable |
2. UNS N06625 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Nickel (Ni) | 58.0 min |
| Chromium (Cr) | 20.0 – 23.0 |
| Molybdenum (Mo) | 8.0 – 10.0 |
| Niobium + Tantalum (Nb+Ta) | 3.15 – 4.15 |
| Iron (Fe) | 5.0 max |
| Carbon (C) | 0.10 max |
| Manganese (Mn) | 0.50 max |
| Silicon (Si) | 0.50 max |
| Phosphorus (P) | 0.015 max |
| Sulfur (S) | 0.015 max |
| Aluminum (Al) | 0.40 max |
| Titanium (Ti) | 0.40 max |
| Cobalt (Co) | 1.0 max |
Grade 2 (Commercial) vs. Aviation Grade Comparison
| Parameter | Grade 2 (Commercial) | Aviation Grade (AMS 5666) |
|---|---|---|
| Phosphorus (P) | ≤ 0.015% | ≤ 0.010% |
| Sulfur (S) | ≤ 0.015% | ≤ 0.005% |
| Oxygen (O) | Not specified | ≤ 30 ppm |
| Nitrogen (N) | Not specified | ≤ 50 ppm |
| Hydrogen (H) | Not specified | ≤ 5 ppm |
| Melting Process | VIM + ESR | VIM + VAR (double melt – mandatory) |
| Grain Size | ASTM 5 or finer | ASTM 6 or finer |
| Non-metallic Inclusions | ≤ 2.0 (ASTM E45) | ≤ 1.0 (ASTM E45) |
3. Mechanical properties of Inconel 625 Grade 2 (solution annealed)
| Property | Minimum Value |
|---|---|
| Tensile Strength (Rm) | 100 ksi (690 MPa) |
| Yield Strength (0.2% offset) | 40 ksi (276 MPa) |
| Elongation (in 2″) | 30% |
| Hardness (Brinell) | ≤ 220 |
Click here to download the Inconel 625 alloy PDF file
4. Inconel 625 Grade 2 Alloy corrosion resistance
| Environment | Resistance Level | Notes |
|---|---|---|
| Oxidizing Acids (HNO₃) | Excellent | - |
| Reducing Acids (H₂SO₄, HCl) | Excellent | High Mo content provides excellent resistance |
| Chloride Pitting | Excellent | - |
| Crevice Corrosion | Excellent | - |
| Chloride Stress Corrosion Cracking | Excellent | - |
| Seawater | Excellent | - |
| High-Temperature Oxidation (to 980°C) | Excellent | - |
| Sour Gas (H₂S/CO₂) | Excellent | NACE MR0175 compliant |
Corrosion Resistance Rating (1-5, 5 = best)
| Environment | Inconel 625 Grade 2 |
|---|---|
| Sulfuric Acid | 5 |
| Hydrochloric Acid | 5 |
| Seawater | 5 |
| Chloride SCC | 5 |
| High-Temp Oxidation (980°C) | 5 |
5. Inconel 625 Grade 2 Alloy Product Dimensions and Specifications
Bar Products
| Diameter (mm) | Length (mm) | Tolerance | Surface |
|---|---|---|---|
| 6 – 25 | 2000 – 6000 | h6 – h8 | Ground / Bright |
| 25 – 50 | 2000 – 6000 | h6 – h8 | Ground / Bright |
| 50 – 100 | 2000 – 4000 | h7 – h9 | Black / Rough Turned |
| 100 – 200 | 1000 – 3000 | h8 – h10 | Black / Rough Turned |
Tube Products
| OD (mm) | Wall Thickness (mm) | Tolerance | Surface |
|---|---|---|---|
| 6 – 30 | 0.5 – 3.0 | ±0.05 – ±0.10 mm | BA / AP |
| 30 – 50 | 1.0 – 5.0 | ±0.10 – ±0.15 mm | BA / AP |
| 50 – 100 | 2.0 – 8.0 | ±0.15 – ±0.30 mm | BA / AP |
Plate Products
| Thickness (mm) | Width (mm) | Length (mm) | Tolerance |
|---|---|---|---|
| 0.5 – 4.0 | 500 – 1200 | 1000 – 3000 | ±5% – ±10% |
| 4.0 – 10.0 | 500 – 1500 | 1000 – 4000 | ±5% – ±10% |
| 10.0 – 25.0 | 500 – 1500 | 1000 – 4000 | ±5% – ±10% |
Contact us to customize Inconel 625 products to fit your project dimensions
6. Inconel 625 Grade 2 Alloy Industrial Applications
If your component is exposed to continuous heat while under mechanical stress, Grade 2 is non-negotiable:
Offshore Flare Stacks: Withstanding open flames and thermal expansion.
Aero-engine Exhaust Systems: Resisting fluctuating thermal fatigue.
Nuclear Reactor Internals: Stable performance in high-purity steam at heat.
Petrochemical Heaters: Maintaining wall thickness and Structural Integrity.
Why Choose Gnee as Your Nickel-Based Alloy Supplier
✅️Direct Factory Price: Eliminate middleman markups and secure the best rates for specialized heat treatments.
✅️Precision Heat Treatment: Every batch is processed in vacuum or atmosphere-controlled furnaces with documented time/temp logs.
✅️Total Traceability: Every pipe/bar is stamped with its grade and heat number, backed by a full EN 10204 3.1 MTC.
✅️Custom Fabrication: We offer precision cutting and centerless grinding (h8-h11) to deliver parts ready for assembly.
Gnee Alloy inconel 625 Certificate
📦 Packaging and Shipping
All Nickel Based Alloy products are packaged using the following methods:
Wooden pallets or crates
Moisture-proof packaging
Labels with furnace number, standard, and size labels
Shipped worldwide by sea, air, or express
Gnee Alloy 625 Product Packing
Contact us for the latest export price quote for inconel 625 Alloy
FAQ
Q1: Can I use Grade 2 for room-temperature corrosive acids?
A: You can, but Grade 1 is usually better for aqueous corrosion. Grade 1 has a finer grain size, which provides higher room-temperature tensile strength and slightly better resistance to some corrosive chemicals.
Q2: Is the price difference significant between Grade 1 and Grade 2?
A: The raw material cost is similar, but Grade 2 involves a more expensive and longer heat treatment cycle. However, for high-temp projects, Grade 2 offers a much higher ROI by preventing catastrophic failure.
Q3: Can Grade 1 be "converted" into Grade 2 later?
A: Technically yes, by re-annealing at 1093°C+. However, this must be done with Tier-1 Quality Control to avoid surface oxidation and dimensional distortion. We recommend purchasing certified Grade 2 from the start.
Q4: Do you provide certification for both grades?
A: Absolutely. Our Mill Test Certificates explicitly state the ASTM Grade (1 or 2) and the annealing temperature to ensure you pass all technical audits.
