Inconel 617 vs. Inconel 625: Which alloy performs better at high temperatures?
Inconel 617 vs. Inconel 625: Which alloy performs better at high temperatures?
Inconel 617 performs better at high temperatures due to its excellent creep resistance, oxidation resistance, and strength up to 1100°C. In contrast, Inconel 625 is more suitable for corrosive and moderate-temperature environments, as its high-temperature strength decreases significantly above 900°C.
What is the maximum operating temperature of Inconel 625?
INCONEL nickel-chromium alloy 625 (UNS N06625/W.Nr. 2.4856) is widely used due to its high strength, excellent machinability (including joining properties), and superior corrosion resistance. Its operating temperature range is from low temperatures to 1800°F (982°C).
Chemical Composition Comparison
| Element | INCONEL 617 (%) | INCONEL 625 (%) | Function in Alloy |
|---|---|---|---|
| Nickel (Ni) | Balance (≥ 44.5) | Balance (58.0 min) | Base metal, corrosion and heat resistance |
| Chromium (Cr) | 20.0 – 24.0 | 20.0 – 23.0 | Improves oxidation and scaling resistance |
| Molybdenum (Mo) | 8.0 – 10.0 | 8.0 – 10.0 | Provides strength and pitting resistance |
| Cobalt (Co) | 10.0 – 15.0 | - | Enhances strength at very high temperatures |
| Iron (Fe) | ≤ 3.0 | 5.0 max | Minor strengthening element |
| Niobium (Nb + Ta) | - | 3.15 – 4.15 | Adds solid-solution and precipitation hardening |
| Aluminum (Al) | 0.8 – 1.5 | 0.40 max | Improves oxidation resistance |
| Titanium (Ti) | ≤ 0.6 | 0.40 max | Contributes to stabilization and strength |
| Carbon (C) | 0.05 – 0.15 | 0.10 max | Increases creep rupture strength |
Mechanical Properties Comparison
| Property | INCONEL 617 | INCONEL 625 |
|---|---|---|
| Density | 8.36 g/cm³ | 8.44 g/cm³ |
| Tensile Strength (Room Temp) | 890 MPa | 930 MPa |
| Yield Strength (0.2% offset) | 440 MPa | 450 MPa |
| Elongation | 45% | 45% |
| Hardness (Brinell) | ~170 HB | ~200 HB |
| Operating Temperature Limit | Up to 1100°C | Up to 980°C |
| Melting Range | 1330–1380°C | 1290–1350°C |
INCONEL 617 maintains its strength and stability above 1000°C, while INCONEL 625 exhibits excellent strength and corrosion resistance below 980°C.
High Temperature Performance
INCONEL 617
Developed specifically for extreme high-temperature applications.
Due to its cobalt and aluminum content, it maintains mechanical strength even above 1000°C.
Exhibits excellent oxidation and creep resistance in air or combustion gas environments.
Commonly used in gas turbines, reformers, and heat exchangers.
INCONEL 625
Performs best in temperatures below 980°C.
Above this temperature limit, its strength decreases faster than INCONEL 617.
Suitable for medium-temperature corrosive environments, such as chemical plants, offshore equipment, and ship components.
Oxidation Resistance and Corrosion Resistance
Oxidation Resistance
INCONEL 617: Excellent oxidation resistance due to its high chromium and aluminum content; forms a robust oxide film, preventing scaling at temperatures up to 1100°C.
INCONEL 625: Excellent oxidation resistance, but performance decreases slightly above 1000°C.
Corrosion Resistance
INCONEL 625: Performs well in aqueous, chloride, and acidic environments (especially seawater and chemical plants).
INCONEL 617: Performs best in oxidizing and carburizing atmospheres, but its corrosion resistance under acidic conditions is not as good as 625.
Summary:
Heat Resistance: Choose INCONEL 617; Corrosion Resistance: Choose INCONEL 625.
Why Choose Gnee as Your Nickel-Based Alloy Supplier
✅ Over 18 years of export experience, products sold to more than 80 countries
✅ Certified by ISO, SGS, and BV
✅ Global inventory of Inconel, Hastelloy, Incoloy, and Monel alloy tubing, plates, and bars
✅ Custom processing services available – including cutting, polishing, CNC machining, and packaging
✅ Fast delivery within 7-15 days, supported by global logistics partners
📦 Packaging and Shipping
All stainless steel 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 Steel is a supplier of GH4169 alloy, offering a wide range of products including: seamless pipe (sizes: 4-219 mm; thickness: 0.5-20 mm); welded pipe (sizes: 5.0-1219.2 mm; thickness: 0.5-20 mm); plates (thickness: 0.1 to 100 mm; width: 10-2500 mm); strips; alloy round bars (diameter: 3-800 mm); flat bars (thickness: 2-100 mm; width: 10-500 mm); hexagonal bars (size: 2-100 mm); wire rods; and extruded profiles. We collaborate with steel mills to provide our customers with GH4169 alloy products that meet or exceed numerous leading industry standards, including ASTM, ASME, SAE, AMS, ISO, DIN, EN, and BS standards.
Gnee Steel stocks and sells GH4169, pipes, plates, strips, round bars, flat bars, forged billets, hexagonal steel, wire rods, and extruded profiles. Please feel free to contact us at ss@gneesteel.com for a quote.
