Hastelloy X vs Inconel 718 – What’s the Difference

Hastelloy X vs Inconel 718

Two popular options come to mind when looking for high-performance materials that can withstand extreme conditions and environments: Hastelloy X and Inconel 718. Both materials are widely used in industries requiring robust and durable alloys. However, there are significant differences between them that can impact their performance. In this article, we will dive deep into the characteristics, properties, and applications of Hastelloy X and Inconel 718 to help you decide which is best suited for your needs.

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Difference Between Hastelloy X and Inconel 718

Composition and Properties

Hastelloy X and Inconel 718 are nickel-based alloys, but their compositions differ. Hastelloy X contains significant amounts of nickel, chromium, molybdenum and smaller amounts of iron, cobalt, and tungsten. Its high molybdenum and chromium content makes it highly resistant to oxidation and corrosion, even at high temperatures of up to 1200 degrees Celsius. On the other hand, Inconel 718 contains nickel, chromium, iron, and niobium, with smaller amounts of molybdenum, titanium, and aluminium. Its high tensile strength, fatigue resistance, and toughness make it an excellent material for aerospace and gas turbine components.


Due to their unique properties, Hastelloy X and Inconel 718 find their applications in various industries. Hastelloy X is commonly used in the chemical processing and petrochemical industries, where it can withstand high temperatures and corrosive environments. Its resistance to sulfidation and carburization makes it an ideal material for combustors and exhaust systems in power generation and aviation. Inconel 718 is widely used in the aerospace and automotive industries, where it is used in turbine blades, rocket components, and fuel injectors. Its high-temperature properties and resistance to high-pressure steam make it a popular material in the nuclear industry.


When it comes to weldability, Hastelloy X and Inconel 718 differ significantly. Hastelloy X has poor weldability due to its high carbon content, which can lead to cracking and brittleness during welding. Therefore, it requires preheating, post-weld heat treatment, and careful selection of welding parameters to ensure a successful weld. In contrast, Inconel 718 has excellent weldability due to its low carbon content and the presence of niobium, which acts as a grain refiner and enhances the weldability of the material.


Hastelloy X and Inconel 718 are difficult to machine due to their high alloy content and hardness. However, Inconel 718 is slightly easier to machine than Hastelloy X due to its lower hardness and better thermal conductivity. Machining of both materials requires specialized tools and techniques, including low cutting speeds, high lubrication, and coolant flow.


Finally, the cost of Hastelloy X and Inconel 718 also differs. Hastelloy X is generally more expensive than Inconel 718 due to its higher content of expensive metals such as molybdenum, nickel, and chromium. Inconel 718, on the other hand, is more affordable and readily available, making it a popular choice for budget-conscious applications that require high-performance materials.


In conclusion, Hastelloy X and Inconel 718 are excellent materials with unique properties and applications. While Hastelloy X is more resistant to corrosion and oxidation at high temperatures, Inconel 718 has superior weldability and machinability. The choice between these materials depends on the specific requirements of your application, including environmental, mechanical, and economic factors. Knowing the differences between Hastelloy X and Inconel 718 can help you decide and select the right material for your needs.



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