Inconel 800 vs Incoloy 800: Composition, Properties, and Applications
When it comes to high-performance alloys, the names Inconel 800 and Incoloy 800 often surface in discussions about durability and…
In the world of engineering and industrial applications, choosing the right material can significantly impact the performance and longevity of your projects. Enter Incoloy 800 and SS 310, two heavyweights in the realm of high-performance alloys. But how do these materials stack up against each other, and which one is the ideal choice for your specific needs? This comprehensive guide delves into the nitty-gritty of their chemical compositions, mechanical properties, and applications across diverse industries. From heat exchangers to industrial furnaces, understanding the nuances of these alloys is crucial for making informed decisions. We’ll explore their corrosion resistance, high-temperature capabilities, and cost considerations, providing you with a detailed comparison to navigate the complexities of material selection. Whether you’re an engineer, material scientist, or industrial user, this article will equip you with the knowledge to choose the most suitable alloy for your next project.
Incoloy 800 is a nickel-iron-chromium alloy known for its excellent performance in high-temperature and corrosive environments. It consists of 30-35% nickel, 19-23% chromium, at least 39.5% iron, and small amounts of aluminum and titanium. This combination imparts exceptional resistance to oxidation, carburization, and various forms of corrosion, making Incoloy 800 a reliable choice in challenging industrial settings.
Incoloy 800 stands out for its remarkable strength and stability at high temperatures, retaining its integrity even in environments up to 815°C (1500°F). Its resistance to cracking under stress and ability to endure carburizing conditions make it ideal for heat treatment and chemical processing applications.
Incoloy 800 is commonly used in high-temperature applications such as ethylene furnace quench boilers, hydrocarbon cracking, industrial furnaces, heat-treating equipment, chemical processing (especially with nitric acid), and power plant super-heaters and re-heaters.
Stainless Steel 310 is an austenitic stainless steel that combines good high-temperature properties with moderate corrosion resistance. Its composition predominantly includes chromium (24-26%) and nickel (19-22%), with iron as the primary element. This makeup enables SS 310 to withstand temperatures up to 1150°C (2100°F), making it suitable for applications requiring robust thermal stability.
SS 310 is known for its high resistance to oxidation and its ability to maintain structural integrity at high temperatures. However, it exhibits less resistance to chloride stress-corrosion cracking compared to Incoloy 800. Despite this, SS 310 remains a popular choice for environments where temperature resistance is prioritized over exposure to aggressive chemical agents.
SS 310 is widely employed in furnace components, heat exchangers, pressure vessels, petrochemical and chemical processing equipment, and aerospace components.
Both Incoloy 800 and SS 310 excel in high-temperature applications. Incoloy 800 is preferred for its outstanding resistance to oxidation, carburization, and corrosion, especially in corrosive chemical environments. On the other hand, SS 310 is chosen for its excellent oxidation resistance and strength at high temperatures in less chemically aggressive settings. Understanding these distinctions is crucial for selecting the appropriate alloy for specific industrial needs.
Incoloy 800 is a nickel-iron-chromium alloy known for its strength at high temperatures and resistance to oxidation and carburization. This alloy features:
Incoloy 800H maintains similar properties with slight variations in composition:
Incoloy 800HT offers enhanced strength with:
Stainless Steel 310, an austenitic stainless steel, is noted for its high chromium and nickel content, offering excellent oxidation resistance and moderate corrosion resistance. It includes:
Stainless Steel 310S features:
Stainless Steel 310H is designed for enhanced performance with:
These differences in chemical composition are crucial in determining:
The variations in nickel and chromium content, along with the presence or absence of elements like aluminum and titanium, dictate the unique capabilities and uses of Incoloy 800 and Stainless Steel 310 series alloys.
Incoloy 800 and Stainless Steel 310 are renowned for their excellent mechanical properties, making them ideal for high-temperature applications.
Incoloy 800 boasts high tensile properties both at room and elevated temperatures, with a tensile strength of approximately 86.5 ksi (596 MPa) at room temperature. Similarly, Stainless Steel 310 has a minimum tensile strength of 75 ksi (517 MPa) at room temperature, though it decreases at higher temperatures. For example, Stainless Steel 310’s tensile strength drops to 67.8 ksi (467 MPa) at 1000°F (538°C) and 19.1 ksi (132 MPa) at 1600°F (871°C).
Both Incoloy 800 and Stainless Steel 310 have comparable yield strengths at room temperature, around 30 ksi (207 MPa). However, Incoloy 800 retains its yield strength better at elevated temperatures. For instance, Incoloy 800’s yield strength decreases to 20.7 ksi (143 MPa) at 1200°F (650°C), whereas Stainless Steel 310’s yield strength drops to 20.8 ksi (143 MPa) at 1000°F (538°C) and further to 12.2 ksi (84 MPa) at 1600°F (871°C).
Incoloy 800 shows good ductility, with an elongation of about 40% at room temperature, meaning it can stretch significantly before breaking. Stainless Steel 310 also maintains good elongation properties, around 40% at room temperature, ensuring it can deform considerably before failing.
Incoloy 800 is renowned for its significant creep and rupture strength, particularly vital for high-temperature applications. The enhanced versions, Incoloy 800H and 800HT, offer even greater resistance to stress rupture and creep, making them suitable for more demanding environments. On the other hand, Stainless Steel 310 exhibits moderate creep-rupture strength, suitable for applications requiring sustained performance under stress at high temperatures.
Incoloy 800 demonstrates excellent fatigue strength, capable of withstanding low-cycle fatigue conditions effectively, especially at elevated temperatures like 1000°F (540°C). It also maintains its toughness even at cryogenic temperatures, with Charpy V-notch impact strengths ranging from 73 to 89 ft-lbf (99-121 J). In contrast, Stainless Steel 310, while robust, does not exhibit the same level of fatigue and impact resistance as Incoloy 800.
When comparing these materials, Incoloy 800 generally retains higher tensile strength and yield strength at elevated temperatures. It also excels in creep and rupture strength, making it more suitable for prolonged high-stress applications. Additionally, Incoloy 800 shows superior fatigue strength and impact resistance, which is beneficial for cyclic loading and low-temperature applications. Both materials offer good ductility, ensuring they can deform significantly before failing.
Incoloy 800 is renowned for its exceptional resistance to various forms of corrosion. Its resistance to stress-corrosion cracking, particularly in chloride environments, sets it apart from many other alloys. The alloy’s composition, rich in nickel and chromium, provides robust protection against intergranular corrosion, scaling, and sulphidation. This makes Incoloy 800 highly suitable for use in environments where exposure to aggressive chemicals and high temperatures is common. For example, Incoloy 800 is often used in chemical plants due to its resistance to harsh conditions. Additionally, it shows high resistance to molten carbonates, molten eutectic salt deposits, hydrogen peroxide, and hydrogen chloride in moist air, making it versatile for a range of industrial applications.
Stainless Steel 310 offers excellent oxidation resistance due to its high chromium and nickel content. This alloy can withstand temperatures up to 2000°F (1093°C) while maintaining its structural integrity. However, it does not perform as well as Incoloy 800 in highly corrosive environments. SS 310 is more susceptible to corrosion in acidic and alkaline conditions, which limits its use in environments where chemical exposure is a significant concern. Despite this, SS 310 remains a preferred choice in applications where oxidation resistance is critical, and chemical exposure is minimal.
Incoloy 800: This alloy is engineered for high-temperature environments, maintaining superior strength to withstand long-term stress at high temperatures up to 1500°F (815°C). It is commonly utilized in industrial incinerators, furnace tubes, and heat processing equipment, where long-term thermal stability is crucial. Incoloy 800’s ability to withstand high temperatures without losing its mechanical properties makes it indispensable in applications requiring sustained performance under extreme heat.
SS 310: Stainless Steel 310 excels in high-temperature applications with its ability to resist oxidation up to 2000°F (1093°C). This makes it ideal for use in furnace components, heat exchangers, and exhaust systems. While SS 310 offers excellent heat resistance, its performance at extremely high temperatures is not as consistent as Incoloy 800, especially in environments that involve corrosive elements.
Incoloy 800 demonstrates excellent resistance to various forms of corrosion, including chloride stress corrosion cracking, sulphidation, and carburization. This resistance makes it highly effective in environments with high chloride exposure or where sulphur and carbon-rich atmospheres are prevalent. On the other hand, SS 310, while resistant to oxidation, does not match the level of resistance to these forms of corrosion exhibited by Incoloy 800.
Corrosion Rate: Incoloy 800 generally exhibits a slower corrosion rate compared to SS 310, particularly in environments involving high temperatures and corrosive substances. For example, in a refinery furnace environment, Incoloy 800H and 800HT show a corrosion rate of 0.15mm/y (6.0mpy), whereas SS 310 has a higher rate of 0.23mm/y (8.9mpy). A lower corrosion rate means longer lifespan and reduced maintenance costs, which is advantageous in industrial applications.
Ability to Withstand Long-Term Stress at High Temperatures: Incoloy 800 and its variants (800H and 800HT) offer significantly higher strength to withstand long-term stress at high temperatures than SS 310. This makes Incoloy 800 more suitable for long-term applications that require materials to withstand prolonged exposure to high stress and temperature.
In summary, while both Incoloy 800 and SS 310 are designed for high-temperature applications, Incoloy 800 provides superior corrosion resistance and higher strength to withstand long-term stress at high temperatures, making it a better choice for environments that combine high heat with aggressive chemical exposure.
Incoloy 800 is well-known for performing exceptionally well in high-temperature and corrosive environments, making it a top choice across various industries.
Incoloy 800 is widely used in chemical processing because it resists corrosion and retains its strength at high temperatures. Typical applications include:
In the power generation sector, Incoloy 800 is valued for its strength and resistance to oxidation and corrosion. It is commonly employed in:
For heat treatment and furnace components, Incoloy 800 is preferred due to its superior high-temperature resistance. SS 310 is better for lower-temperature uses.
The food processing industry benefits from Incoloy 800’s resistance to high temperatures and corrosion, particularly in:
These applications involve harsh chemicals and high temperatures, where Incoloy 800’s properties ensure durability and safety.
In aerospace, Incoloy 800 is used in parts like exhaust systems and gas turbines that face extreme heat and corrosive gases. Its ability to maintain structural integrity at high temperatures contributes to the safety and performance of aircraft.
Stainless Steel 310 is known for its excellent high-temperature properties and moderate corrosion resistance, making it suitable for various industrial applications.
SS 310 is widely used in furnace applications due to its ability to withstand high temperatures up to 1150°C (2100°F). Common uses include:
In the petrochemical and chemical processing industries, SS 310 is employed in:
Its high-temperature stability makes it suitable for these environments, although it is less resistant to corrosive chemicals compared to Incoloy 800.
SS 310 is used in the aerospace industry for components requiring robust thermal stability, such as:
Its ability to resist oxidation at high temperatures ensures reliable performance in these critical applications.
In chemical processing, Incoloy 800 is preferred over SS 310 for its superior corrosion resistance and durability in harsh environments, making it ideal for heat exchangers and reactors.
In power generation, Incoloy 800 is preferred for components exposed to high temperatures and corrosive environments, such as superheater tubing and steam turbines. SS 310 may be used in less demanding roles but does not match the performance of Incoloy 800 in extreme conditions.
For food processing equipment, Incoloy 800 is gaining popularity due to its resistance to high temperatures and corrosion, ensuring safety and durability in sterilization and heat exchange processes. SS 310 is less commonly used due to its lower corrosion resistance.
In aerospace, Incoloy 800 is chosen for critical components that must withstand extreme heat and corrosive conditions. SS 310 is used in applications where high-temperature stability is essential but without the same level of corrosive exposure.
In summary, both Incoloy 800 and SS 310 have their unique strengths and applications across various industries. The choice between them depends on the specific requirements of the application, particularly regarding temperature, corrosion resistance, and environmental conditions.
Incoloy 800 excels in extreme environments thanks to its high nickel and chromium content, but this also makes it more expensive than many other alloys, including Stainless Steel 310. Despite the higher initial cost, Incoloy 800 often proves cost-effective over time due to its durability and minimal maintenance needs. Its longevity in high-temperature and corrosive environments can lead to reduced replacement and repair costs, making it a worthwhile investment for demanding applications.
Stainless Steel 310 offers a more budget-friendly option compared to Incoloy 800, primarily due to its lower nickel and chromium content. The cost of SS 310 varies with factors like thickness, with thicker sheets generally being more expensive. It is a cost-effective choice for applications that do not require the exceptional high-temperature and corrosion resistance of Incoloy 800. However, in certain environments, SS 310 may incur higher maintenance costs, especially if exposed to aggressive chemicals.
The fabrication of Incoloy 800 involves specific processes to maintain its properties. It is typically forged at temperatures between 2200°F and 1600°F (1200°C and 870°C). Heavy forging should be done between 2200°F and 1850°F (1200°C and 1010°C). Temperature control is crucial to prevent chromium carbide precipitation, which can affect its properties. The alloy is annealed at temperatures between 1800°F and 1900°F (980°C and 1040°C), followed by water quenching to achieve optimal strength and corrosion resistance. While Incoloy 800 can be welded using standard techniques, the choice of filler metals and electrodes is critical and should align with supplier recommendations. The machining of Incoloy 800 is more challenging and costly compared to stainless steels, necessitating specialized tools and techniques.
Stainless Steel 310 is easier to fabricate than Incoloy 800 due to its lower hardness and more manageable machining properties. It can be welded using common stainless steel welding practices, which are less complex and less expensive than those required for Incoloy 800. The ease of machining SS 310 makes it a preferred choice for projects with tight budgets and timelines. The thickness of SS 310 sheets can be tailored to suit specific applications, with thicker sheets recommended for areas requiring additional strength and warp resistance. This versatility in fabrication, combined with lower costs, makes SS 310 a practical option for a wide range of applications.
Below are answers to some frequently asked questions:
The primary chemical differences between Incoloy 800 and SS 310 are their nickel, chromium, iron, carbon, and additional element contents. Incoloy 800 contains 30.0-35.0% nickel and 19.0-23.0% chromium, with a minimum of 39.5% iron, and includes aluminum and titanium. SS 310 has 19.0-22.0% nickel and 24.0-26.0% chromium, with the balance being iron, and a higher maximum carbon content of 0.25%. Unlike Incoloy 800, SS 310 does not contain significant amounts of aluminum and titanium. These differences impact their suitability for various high-temperature and corrosive environments.
Incoloy 800 and Stainless Steel 310 both offer strong mechanical properties, but they excel in different areas. Incoloy 800 is known for its high mechanical strength over a broad temperature range, particularly with its 800H and 800HT variants, which provide superior creep and rupture strengths at elevated temperatures. Stainless Steel 310, while also strong, is particularly noted for its excellent high-temperature strength and corrosion resistance. It maintains significant strength up to 1300°F (704°C) and is suitable for environments requiring durability and oxidation resistance. The choice depends on the specific application needs, particularly regarding temperature and environmental conditions.
Incoloy 800 is predominantly used in the chemical and petrochemical industries, power plants, industrial furnaces, the marine industry, oil and gas, paper pulp, and medical fields due to its excellent resistance to corrosion and high temperatures. SS 310 is commonly employed in industrial furnaces, heat-treating equipment, power plants, chemical processing, and aerospace sectors, where its high-temperature oxidation resistance is crucial. While both materials serve high-temperature and corrosive environments, Incoloy 800 is favored for broader corrosive resistance, and SS 310 is selected for its superior high-temperature stability.
Incoloy 800 generally demonstrates superior corrosion resistance compared to SS 310. Incoloy 800 excels in resisting corrosion in a wide range of environments, including high-temperature and acidic conditions, thanks to its nickel-iron-chromium composition. It outperforms SS 310 in hostile environments such as refinery furnaces and is highly resistant to chloride stress corrosion cracking and embrittlement. While SS 310 offers excellent oxidation resistance at high temperatures, its corrosion resistance in acidic or alkaline environments is not as robust as that of Incoloy 800.
There is a significant cost difference between Incoloy 800 and SS 310, with Incoloy 800 being more expensive due to its complex composition and higher nickel and chromium content. These elements, particularly nickel, contribute to its increased cost. Incoloy 800’s superior performance in high-temperature and corrosive environments can justify the additional expense for applications that demand these characteristics. Conversely, SS 310 offers a more cost-effective option for less demanding applications, providing excellent corrosion resistance and mechanical properties at a lower price. The choice should consider both performance requirements and budget constraints.
