What is the difference between Inconel 625 and 718 Alloy?
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What is the difference between Inconel 625 and 718 Alloy?
The main difference lies in their composition: Inconel 625 is known for its high corrosion resistance, while Inconel 718 is renowned for its superior strength and hardness. This is due to their different compositions: 625 has a higher content of nickel, chromium, and molybdenum, making it more resistant to corrosive environments; while 718 is strengthened through precipitation hardening and has a higher content of niobium and titanium, giving it excellent mechanical properties at high temperatures.
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What are the uses of Inconel 625?
Inconel 625 has excellent weldability and formability, so it is often processed into pipes, plates, flanges, and bars, making it an ideal material for applications such as offshore pipeline systems, heat exchangers, chemical transport pipelines, and gas turbine pipeline systems.
Difference Between Inconel 625 and 718
Mechanical Properties of Inco 718 & 625
| Properties | Inconel 625 | Inconel 718 |
|---|---|---|
| Elongation at Break | 33 to 34 % | 12 to 50 % |
| Poisson's Ratio | 0.29 | 0.29 |
| Shear Strength | 530 to 600 MPa (77 to 87x 103psi) | 660 to 950 MPa (96 to 140x 103psi) |
| Yield Strength | 320 to 450 MPa (47 to 65x 103 psi) | 510 to 1330 MPa (74 to 190 x 103 psi) |
| Elastic Modulus | 190 GPa (28 x 106 psi) | 200 GPa (30 x 106 psi) |
| Fatigue Strength | 240 to 320 MPa (34 to 47 x 103 psi) | 460 to 760 MPa (67 to 110 x 103 psi) |
| Shear Modulus | 530 to 600 MPa (77 to 87 x 103 psi) | 75 GPa (11 x 106 psi) |
| Tensile Strength | 790 to 910 MPa (120 to 130 x 103 psi) | 930 to 1530 MPa (130 to 220 x 103 psi) |
Heat Treatment Comparison
Inconel 625
| Heat Treatment | Temperature (°C) | Duration | Microstructural Change | Mechanical Effect |
|---|---|---|---|---|
| Solution Annealing | 1100 | 6 h | Equiaxed grains, twins | Baseline structure |
| Prolonged Heat | 800–1050 | >0.5 h | Carbide formation | Alters hardness/ductility |
Inconel 718
| Heat Treatment | Temperature (°C) | Mechanical Properties | Microstructural Effect |
|---|---|---|---|
| Solution + Double Aging | 1050 (solution), aging steps | Tensile: up to 1270 MPa Yield: 970 MPa Plasticity: 13.9% |
Precipitation of γ" and γ', dissolution of δ phase, refined grains |
Standards Comparison
| Product Form | Inconel 625 Standards | Inconel 718 Standards |
|---|---|---|
| Seamless Pipe and Tube | ASTM B444, ASTM B829 | SAE AMS 5589, SAE AMS 5590 |
| Welded Pipe | ASTM B705, ASTM B775 | N/A |
| Welded Tube | ASTM B704, ASTM B751 | N/A |
| Welded Fittings | ASTM B366 | N/A |
| Rod and Bar | ASTM B446 | ASTM B637, SAE AMS 5662, SAE AMS 5663, SAE AMS 5664 |
| Forgings | ASTM B564 | ASTM B637, SAE AMS 5662, SAE AMS 5663, SAE AMS 5664 |
| Plate, Sheet, and Strip | ASTM B443 | ASTM B670, ASTM B906, SAE AMS 5596, SAE AMS 5597, SAE AMS 5950 |
| Round Bar and Wire | N/A | SAE AMS 5962 |
| Welding Wire | N/A | SAE AMS 5832 |
Comparison of Applications
Applicable Industries
Aerospace
Inconel 625: Corrosion Resistance in Harsh Environments
Inconel 625's exceptional corrosion resistance makes it an indispensable material in the harsh environments of the aerospace industry. Its excellent resistance to oxidation and chemical corrosion ensures the reliable performance of components such as exhaust systems and thrust reversers. These components are frequently exposed to corrosive gases and extreme temperatures, and Inconel 625 excels due to its high chromium and molybdenum content. This alloy offers long-term durability, reducing maintenance requirements and improving operational efficiency.
Inconel 718: High Strength and Heat Resistance for Engine Components
Inconel 718 is the material of choice for aerospace engine components due to its superior strength and heat resistance. It maintains mechanical integrity at temperatures up to 1300°F (704°C), making it ideal for critical components such as turbine blades and turbine disks. These components endure high stress and extreme temperatures, and Inconel 718's precipitation hardening mechanism ensures their reliability. Its ability to resist creep and maintain stability under such conditions makes it a cornerstone material for aerospace engineering.
Oil & Gas
Inconel 625: Ideal for Subsea and Marine Applications
Inconel 625 offers exceptional corrosion resistance, making it the preferred material for subsea and marine applications. It excels in high-salinity and high-pressure environments, such as pipelines, valves, and subsea equipment. Its resistance to pitting and crevice corrosion ensures durability even under the most demanding conditions. This alloy withstands chemical corrosion and mechanical stress, making it a reliable material for long-term use in the oil and gas industry.
Inconel 718: Suitable for High-Stress Environments
Inconel 718 excels in the high-stress environments of the oil and gas industry. Its superior mechanical strength and high-temperature stability make it suitable for critical applications such as high-pressure wellhead components, blowout preventer (BOP) components, and subsea equipment. The alloy's creep resistance and high-temperature performance ensure reliability in harsh operations. Its ability to withstand extreme conditions reduces the risk of failure, thereby improving safety and efficiency.
| Application Type | Description |
|---|---|
| High-pressure wellhead components | Used in critical high-stress environments. |
| Critical downhole tools | Essential for operations in harsh conditions. |
| BOP components | Vital for blowout prevention in drilling. |
| Subsea equipment | Designed to withstand underwater pressures. |
| High-pressure pump components | Required for efficient fluid transport. |
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 Inconel 625 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 Inconel 625 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 Inconel 625, 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.
