Inconel 625 is a nickel-chromium-molybdenum alloy with excellent corrosion resistance and good weldability. It is widely used in marine, chemical processing, and offshore applications.
Inconel 718 is a precipitation-hardened nickel alloy with much higher mechanical strength and better creep resistance at elevated temperatures. It is commonly used in aircraft engines, gas turbines, and other high-stress components.
A corrosion-resistant nickel-chromium-molybdenum alloy with high strength and excellent fatigue resistance, widely used in marine systems, chemical processing, aerospace equipment and offshore applications.
View Inconel 625A precipitation-hardenable nickel-chromium-iron superalloy offering exceptional strength at elevated temperatures, widely used in gas turbines, aircraft engines, rocket components and high-performance fasteners.
View Inconel 718Review the key differences before confirming chemical media, product form, standard, certificate and delivery schedule.
| Comparison Item | Inconel 625 | Inconel 718 | Selection Note |
|---|---|---|---|
| Basic Information | |||
| UNS Number | N06625 | N07718 | Use the UNS number on drawings, MTCs and purchase specifications. |
| Alloy Type | Nickel-chromium-molybdenum-niobium alloy | Nickel-chromium-iron-niobium-molybdenum alloy | 625 is primarily selected for corrosion resistance; 718 is selected for very high mechanical strength. |
| Strengthening Method | Solid-solution strengthened | Precipitation hardened | 718 requires the specified solution and aging treatment to develop its high strength. |
| Typical Product Forms | Plate, sheet, pipe, tube, bar, wire, forgings and fittings | Plate, sheet, bar, wire, forgings, rings and fasteners | 625 is common in corrosion-resistant piping; 718 is especially common in forgings and high-strength components. |
| Chemical Composition | |||
| Nickel (Ni) | 58.0% min | 50.0–55.0% | Both are nickel-based alloys, but 625 normally contains more nickel. |
| Chromium (Cr) | 20.0–23.0% | 17.0–21.0% | The higher chromium range of 625 supports strong general oxidation and corrosion resistance. |
| Molybdenum (Mo) | 8.0–10.0% | 2.8–3.3% | 625 contains substantially more molybdenum, improving resistance to pitting and crevice corrosion. |
| Niobium + Tantalum (Nb + Ta) | 3.15–4.15% | 4.75–5.50% | In 718, niobium is a key contributor to precipitation hardening and high strength. |
| Iron (Fe) | 5.0% max | Balance | 718 contains considerably more iron than 625. |
| Titanium (Ti) | 0.40% max | 0.65–1.15% | Titanium contributes to the precipitation-hardening response of 718. |
| Aluminum (Al) | 0.40% max | 0.20–0.80% | Aluminum works with titanium and niobium in the strengthening system of 718. |
| Carbon (C) | 0.10% max | 0.08% max | Final composition limits must follow the applicable product specification. |
| Mechanical Properties | |||
| Typical Condition | Solution annealed | Solution treated and precipitation hardened | Mechanical values cannot be compared meaningfully without identifying the heat-treatment condition. |
| Yield Strength, RT | Approx. 414 MPa | Approx. 1,035 MPa | Typical minimum values for common specifications; aged 718 is substantially stronger. |
| Tensile Strength, RT | Approx. 827 MPa | Approx. 1,275 MPa | 718 is generally preferred for highly loaded structural components. |
| Elongation, RT | Approx. 30% | Approx. 12% | 625 normally provides greater ductility, while aged 718 provides much higher strength. |
| Creep and Fatigue Strength | Good | Excellent | 718 is preferred for cyclic loading and sustained high-temperature stress. |
| Weldability | Excellent with qualified procedures | Good, but heat treatment and cracking risks require tighter control | For 718, confirm welding sequence, filler metal and post-weld heat-treatment requirements. |
| Price Comparison | |||
| Relative Material Cost | High | High | 625 can carry higher alloying cost, while 718 may incur greater forging, machining and heat-treatment costs. |
| Fabrication Cost | High | High to higher | The high strength of aged 718 makes machining more difficult and heat treatment adds processing cost. |
| Stock Availability | Strong availability in plate, pipe, tube, bar and fittings | Strong availability in bar, forgings, rings, sheet and aerospace specifications | Availability depends heavily on product form, size, specification and required heat-treatment condition. |
| Quotation Factors | Form, size, quantity, specification, testing and nickel/molybdenum prices | Form, size, quantity, heat treatment, testing, machining and aerospace approvals | Request quotations using the actual drawing, tolerances, certification and delivery requirements. |
| Performance & Application | |||
| Corrosion Resistance | Excellent resistance to pitting, crevice corrosion, seawater and many aggressive chemicals | Good general corrosion and oxidation resistance | 625 is normally the better choice when corrosion resistance is the primary requirement. |
| High-Temperature Strength | Good strength and oxidation resistance at elevated temperatures | Excellent strength up to approximately 650°C | 718 is preferred for highly stressed components operating at moderately elevated temperatures. |
| Typical Applications | Marine equipment, offshore piping, chemical processing, exhaust systems and pollution-control equipment | Gas-turbine parts, aerospace engines, rocket components, high-strength fasteners and oilfield equipment | 625 is common in corrosive fluid systems; 718 is common in high-load rotating and structural parts. |
| Best Use Case | Severe corrosion and chloride service requiring good strength and weldability | High-load applications requiring exceptional tensile, fatigue and creep strength | Select according to the dominant design requirement: corrosion resistance for 625 or mechanical strength for 718. |
Values are typical references for article comparison. Final supply should follow the ordered standard, product form, heat treatment, mill test certificate and project requirements.
English English 
French
German
Italian
Spanish
Portuguese
Arabic
Korean