What is the difference between Inconel 800 and Inconel 625?
What is Incoloy 800?
Incoloy 800 is a versatile alloy designed for applications that require excellent corrosion, high strength, and heat resistance. It has exceptional properties such as excellent creep rupture strength and excellent oxidation resistance up to 1050°C (1922°F). This makes it ideal for use in harsh environments such as petroleum refining.
What is Inconel 625?
Inconel 625 is a nickel-based super alloy known for its excellent strength and high-temperature corrosion resistance. It is ideal for seawater, chemical processing, heat exchangers, and more. Its many beneficial properties make it an invaluable material in numerous industries around the world.
Difference between Incoloy 800 and Inconel 625
Composition
Incoloy 800 is a nickel-iron-chromium alloy that has strong resistance to oxidation, carburization, and sulfidation. Its nominal composition includes 32% nickel, 46% iron, 21% chromium, and 0.5% manganese. It also contains trace amounts of aluminum, titanium, and copper. In contrast, Inconel 625 is a nickel-chromium-molybdenum alloy that has excellent corrosion resistance in many environments. Its nominal composition includes 58% nickel, 22% chromium, 9% molybdenum, 3.5% niobium, and 1% iron. It also contains trace amounts of titanium, aluminum, and cobalt. Therefore, Incoloy 800 has a higher iron content and a lower nickel content than Inconel 625.
Properties
The mechanical and physical properties of Incoloy 800 and Inconel 625 differ slightly. Incoloy 800 has higher yield strength, tensile strength, and elongation than Inconel 625 at both room and elevated temperatures. It also has a lower coefficient of thermal expansion, lower thermal conductivity, and higher specific heat capacity than Inconel 625. However, Inconel 625 has a higher melting point, better fatigue resistance, and excellent corrosion resistance than Incoloy 800 in many corrosive environments such as chlorides, fluorides, and acidic solutions.
Applications
Incoloy 800 and Inconel 625 are widely used in different industries due to their unique properties. Incoloy 800 is used in high temperature and corrosive environments such as heat exchangers, petrochemical processing, power generation, and furnace components. Its high resistance to oxidation and carbonization makes it suitable for ethylene cracker tubes, steam methane reformers, and coal-fired power plants. On the other hand, Inconel 625 is used in extreme environments such as marine, aerospace, chemical processing, and nuclear reactors. Its excellent resistance to pitting, crevice, and intergranular corrosion makes it suitable for seawater piping, aircraft piping, heat shields, and reactor core applications.
Costs
The costs of Incoloy 800 and Inconel 625 vary depending on the specific grade, form, and quantity required. In general, Incoloy 800 is less expensive than Inconel 625 due to its lower nickel content and simpler production process. However, for some applications, the cost difference may be insignificant, especially when other factors such as performance, availability and maintenance are taken into account.
