Discover the latest trends and innovations in the nickel alloy industry. We provide expert insights and in-depth analysis on the newest developments in nickel alloys.
Hastelloy and Inconel are two of the most well-known families of nickel-based superalloys. Both are designed to deliver outstanding performance under harsh environmental conditions involving high temperatures, pressure, and chemical exposure. However, their chemical compositions, mechanical behavior, and ideal use cases differ significantly. Understanding the difference between Hastelloy and Inconel helps engineers choose the right alloy for long-term durability and cost-effectiveness.
Hastelloy is primarily a nickel-molybdenum-chromium alloy. The combination of these elements gives it superior resistance to both oxidizing and reducing chemicals. Molybdenum enhances resistance to pitting and crevice corrosion, while chromium protects against oxidizing media such as acids and chlorine compounds. Some grades also include iron, tungsten, or cobalt for added strength and stability. Common grades include Hastelloy C-22 (UNS N06022) and Hastelloy C-276 (UNS N10276).
Inconel is a nickel-chromium alloy with varying amounts of iron, molybdenum, niobium, or titanium depending on the grade. Its composition focuses on high-temperature stability and oxidation resistance. The most widely used grades include Inconel 600, Inconel 625, and Inconel 718, each tailored for specific thermal and mechanical requirements.
Hastelloy is specifically engineered for superior corrosion resistance in chemical environments. It performs exceptionally well in strong oxidizing and reducing acids, including hydrochloric, sulfuric, phosphoric, and nitric acids. It also resists localized corrosion such as pitting and stress corrosion cracking in chloride-bearing solutions, making it ideal for chemical and marine industries.
Inconel is also corrosion-resistant but is primarily optimized for oxidation resistance at high temperatures. It performs well in mildly corrosive environments, saltwater exposure, and oxidizing conditions like hot combustion gases, but it is less resistant to strong reducing acids compared to Hastelloy.
Inconel excels in high-temperature applications. It can retain mechanical strength, creep resistance, and oxidation stability at temperatures exceeding 1000°C. Inconel 625 and Inconel 718, for example, are widely used in jet engines, gas turbines, and nuclear reactors because of their exceptional high-temperature strength.
Hastelloy can also handle elevated temperatures but is generally optimized for chemical corrosion rather than extreme thermal loading. Most Hastelloy grades perform effectively up to about 980°C, which makes them suitable for chemical reactors, heat exchangers, and pollution control systems rather than combustion or aerospace environments.
Hastelloy offers a good combination of ductility, weldability, and moderate high-temperature strength. Its toughness and ease of fabrication make it ideal for chemical plant components that need to be shaped or welded into complex designs.
Inconel provides significantly higher tensile strength and creep resistance, especially at elevated temperatures. However, its hardness and work-hardening tendency make it more difficult to machine or form. Special techniques and tools are required for fabrication.
Hastelloy is commonly used in chemical processing, marine engineering, and pollution control equipment. Typical components include heat exchangers, evaporators, reaction vessels, flue gas scrubbers, and piping systems that handle corrosive fluids.
Inconel is widely used in aerospace, power generation, and marine propulsion industries. It is found in jet engines, turbine blades, exhaust systems, nuclear reactors, and other applications requiring extreme heat and oxidation resistance.
Hastelloy is relatively easy to fabricate and weld compared to other superalloys. It maintains good ductility during forming and resists cracking during welding, provided proper techniques are used.
Inconel is more challenging to fabricate due to its tendency to work-harden quickly. Machining requires rigid equipment and low cutting speeds, and welding must be performed carefully to avoid cracking or deformation. Despite the challenges, its performance at high temperatures often justifies the difficulty and cost.
Hastelloy is generally more expensive per kilogram than many stainless steels or even some Inconel grades because of its high molybdenum and chromium content. However, it provides unmatched chemical resistance, which can reduce long-term maintenance and replacement costs in corrosive environments.
Inconel is also expensive due to its high nickel content and complex production process. It is often chosen for critical aerospace and nuclear applications where material failure is not an option, making the investment worthwhile for safety and performance reasons.
Hastelloy is best for aggressive chemical environments requiring maximum corrosion resistance, while Inconel is superior for high-temperature, high-stress applications requiring mechanical stability. In short, Hastelloy is the preferred alloy for chemical processing industries, and Inconel is the choice for aerospace, turbine, and power generation systems.
