Incoloy 825 and Inconel 625 are two high-performance alloys widely used in industries that demand exceptional resistance to corrosion, high temperatures, and harsh environments. Both alloys have unique properties that make them suitable for different applications, but their distinct characteristics can determine which is the best choice for specific needs. In this article, we will compare Incoloy 825 and Inconel 625, focusing on their composition, mechanical properties, corrosion resistance, and typical applications. By the end, you will have a clearer understanding of which alloy is best suited for your specific requirements. SASAALLOY offers a range of high-quality alloys, including both Incoloy 825 and Inconel 625, to meet the demands of various industries.
What is Incoloy 825?
Incoloy 825 is a nickel-iron-chromium alloy with additions of molybdenum and copper. This combination of elements gives Incoloy 825 its outstanding resistance to a wide range of corrosive environments, including sulfuric and phosphoric acids. It also offers excellent resistance to stress corrosion cracking, pitting, and crevice corrosion, making it ideal for industries like chemical processing, pollution control, and waste treatment.
Incoloy 825 has a unique balance of properties, which includes excellent weldability and formability. These characteristics make it suitable for applications where complex shapes and joints are needed. Its high resistance to corrosion, combined with good mechanical strength and ease of fabrication, positions Incoloy 825 as an excellent choice for numerous industrial applications.
What is Inconel 625?
Inconel 625 is a nickel-chromium alloy containing molybdenum and niobium. It is known for its outstanding fatigue and thermal-fatigue strength, excellent weldability, and resistance to oxidation and corrosion in extreme environments. Inconel 625 is often used in aerospace, marine, and chemical industries due to its excellent performance in high-temperature and corrosive environments.
The high molybdenum content in Inconel 625 enhances its resistance to pitting and crevice corrosion, particularly in chloride environments. In addition, its niobium content allows it to maintain high strength even at elevated temperatures, which makes it a go-to material for applications exposed to heat, such as jet engines and gas turbines.
Incoloy 825 vs Inconel 625: Composition Comparison
Both Incoloy 825 and Inconel 625 contain nickel as their primary component, which contributes to their excellent corrosion resistance. However, the differences in their composition give each alloy unique characteristics that are tailored to specific applications.
Incoloy 825 Composition:
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Nickel (Ni): 38-46%
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Chromium (Cr): 19-23%
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Iron (Fe): Balance
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Molybdenum (Mo): 3-5%
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Copper (Cu): 1.5-3%
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Titanium (Ti): 0.6-1.2%
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Aluminum (Al): 0.2-0.6%
Incoloy 825′s composition is designed to offer high resistance to both oxidation and corrosion, particularly in reducing and mildly oxidizing environments. The inclusion of copper and molybdenum enhances its resistance to acids and other aggressive chemicals, while the presence of titanium contributes to better strength at high temperatures.
Inconel 625 Composition:
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Nickel (Ni): 58-63%
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Chromium (Cr): 20-23%
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Molybdenum (Mo): 8-10%
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Niobium (Nb): 3.15-4.15%
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Iron (Fe): Balance
Inconel 625 is designed for high-strength performance in extreme temperatures. The alloy’s high nickel and molybdenum content, combined with niobium, provide exceptional resistance to high-temperature oxidation and corrosion. The alloy’s composition allows it to maintain its mechanical strength even at elevated temperatures, making it suitable for applications in both high-stress and high-temperature environments.
Mechanical Properties of Incoloy 825 vs Inconel 625
The mechanical properties of Incoloy 825 and Inconel 625 are important considerations when selecting an alloy for a specific application. While both alloys offer high strength and excellent resistance to oxidation and corrosion, their mechanical properties differ in certain areas, especially when exposed to high temperatures.
Incoloy 825 Mechanical Properties:
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Tensile Strength: 690 MPa (100 ksi)
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Yield Strength: 275 MPa (40 ksi)
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Elongation: 30% minimum
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Hardness: Rockwell B 85
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Modulus of Elasticity: 200 GPa
Incoloy 825 offers a good balance of strength and ductility, making it suitable for applications where both mechanical strength and the ability to withstand stress and strain are required. While its tensile strength is lower than that of Inconel 625, its ability to maintain formability and toughness under varying conditions gives it an advantage in many corrosion-heavy environments.
Inconel 625 Mechanical Properties:
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Tensile Strength: 1034 MPa (150 ksi)
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Yield Strength: 413 MPa (60 ksi)
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Elongation: 35% minimum
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Hardness: Rockwell B 90
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Modulus of Elasticity: 205 GPa
Inconel 625 has a higher tensile and yield strength than Incoloy 825, which makes it ideal for high-stress applications, especially those exposed to high temperatures. The alloy’s excellent fatigue and thermal-fatigue strength make it an ideal choice for components in aerospace and power generation industries, where strength at elevated temperatures is a critical requirement.
Corrosion Resistance: Incoloy 825 vs Inconel 625
Both Incoloy 825 and Inconel 625 exhibit excellent corrosion resistance, but they excel in different environments due to their unique compositions. Here’s a closer look at how each alloy performs in various corrosive environments:
Incoloy 825 Corrosion Resistance:
Incoloy 825 is particularly resistant to acids, including sulfuric acid, phosphoric acid, and nitric acid. It also offers excellent protection against stress corrosion cracking, especially in chloride environments. This makes Incoloy 825 a popular choice for chemical processing applications, including reactors, heat exchangers, and storage tanks.
Incoloy 825’s copper content further enhances its resistance to sulfuric acid and reducing environments, making it suitable for pollution control and waste treatment industries where exposure to acidic gases and liquids is common.
Inconel 625 Corrosion Resistance:
Inconel 625 excels in both oxidizing and reducing environments, thanks to its high molybdenum and chromium content. This alloy offers superior resistance to pitting, crevice corrosion, and stress corrosion cracking, especially in environments exposed to chlorides and high temperatures.
Its outstanding resistance to oxidation and corrosion at elevated temperatures makes Inconel 625 ideal for use in aerospace and marine environments, where components experience extreme conditions, such as high temperatures and exposure to seawater or acidic chemicals.
Applications of Incoloy 825 and Inconel 625
Both Incoloy 825 and Inconel 625 are widely used in industries that demand high-performance materials capable of withstanding extreme environmental conditions. However, each alloy is suited to different applications based on its properties.
Applications of Incoloy 825:
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Chemical Processing: Used in reactors, heat exchangers, and pressure vessels due to its excellent resistance to acids and corrosive chemicals.
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Pollution Control: Ideal for applications such as flue gas desulfurization systems, where the material is exposed to acidic gases.
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Waste Treatment: Used in waste incinerators and chemical storage tanks, where corrosion resistance is crucial.
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Marine: Employed in marine environments for components exposed to seawater and other corrosive substances.
Applications of Inconel 625:
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Aerospace: Ideal for components in jet engines, turbine blades, and exhaust systems due to its high-temperature strength and resistance to oxidation.
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Marine: Used in seawater applications, such as marine components and offshore oil rigs, where corrosion resistance and strength are vital.
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Power Generation: Employed in gas turbines and other high-stress applications in the power generation industry.
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Chemical Processing: Used in applications involving highly corrosive environments, including chemical reactors and heat exchangers.
Incoloy 825 vs Inconel 625: Key Differences
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Composition: Incoloy 825 has higher copper content, which enhances its resistance to sulfuric acid and reducing environments. In contrast, Inconel 625 has higher molybdenum and niobium content, making it better suited for high-temperature applications.
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Mechanical Properties: Inconel 625 has higher tensile and yield strength, making it ideal for high-stress and high-temperature environments.
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Corrosion Resistance: While both alloys offer excellent corrosion resistance, Incoloy 825 excels in reducing acids, while Inconel 625 is better for resisting pitting and stress corrosion cracking in chloride environments.
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Applications: Incoloy 825 is ideal for applications in the chemical, pollution control, and waste treatment industries, while Inconel 625 is more suited for aerospace, marine, and power generation industries.
Conclusion
Both Incoloy 825 and Inconel 625 are exceptional materials with unique properties that make them suitable for different industries and applications. Incoloy 825 is ideal for chemical processing and pollution control environments, while Inconel 625 is better suited for high-stress, high-temperature applications in aerospace and power generation.
At SASAALLOY, we offer both Incoloy 825 and Inconel 625 alloys, ensuring that you have access to high-quality materials that meet the demanding standards of your industry. Whether you need excellent corrosion resistance or high-temperature performance, our alloys are designed to deliver exceptional results. Contact us today to learn more about our product offerings and how we can support your industrial needs.
Post time: Jul-25-2025