Incoloy Alloy 330: Properties, Composition, and Uses
In the realm of high-temperature industrial applications, few materials stand out quite like Incoloy Alloy 330. Renowned for its remarkable…
Imagine a material that thrives in the harshest environments, from the depths of the ocean to the heart of chemical processing plants. Incoloy Alloy 25-6MO (UNS N08926) is precisely that—a high-performance alloy designed to withstand extreme conditions with remarkable resilience. Whether you’re an engineer seeking detailed information on its chemical composition or a manufacturer evaluating its mechanical properties, this article offers a comprehensive guide to understanding the unique attributes of Incoloy Alloy 25-6MO. Discover its unparalleled corrosion resistance, explore its diverse applications across various industries, and learn why this alloy is a preferred choice for demanding applications. Ready to dive into the world of Incoloy Alloy 25-6MO and uncover its secrets? Let’s get started.
Incoloy Alloy 25-6MO, known as UNS N08926 and W.Nr 1.4529, is a super-austenitic stainless steel renowned for its exceptional resistance to corrosion in harsh environments. This advanced iron-base alloy is highly valued across various industries due to its robust performance under aggressive and aqueous conditions.
The alloy’s impressive performance stems from its well-balanced chemical composition:
The physical and mechanical properties of Incoloy 25-6MO are summarized below for ease of reference:
Incoloy 25-6MO excels in resisting various forms of corrosion, including pitting and crevice corrosion, which are significant concerns in many industries. Pitting and crevice corrosion occur in localized areas where the metal is exposed to harsh chemical environments, leading to potential material failure. The alloy’s high molybdenum and nitrogen content significantly enhance its resistance, ensuring durability and reliability in demanding conditions.
Thanks to its exceptional properties, Incoloy 25-6MO finds applications across a wide range of industries. It is used in chemical processing equipment, marine and offshore platforms, food processing machinery, paper and pulp bleaching plants, and oil and gas components. Additionally, it is utilized in nuclear power generation systems and air pollution control equipment.
The alloy complies with several industry standards, ensuring its reliability and performance in critical applications. For example, it meets the ASTM B649 standard for wire and bar forms and is universally recognized under UNS N08926.
Incoloy Alloy 25-6MO stands out as a versatile and cost-effective material, offering superior corrosion resistance and making it an ideal choice for various industrial applications where high performance and durability are paramount.
Incoloy Alloy 25-6MO (UNS N08926) is a high-performance stainless steel known for its exceptional corrosion resistance and mechanical properties, thanks to its unique chemical composition.
| Element | Percentage (%) |
|---|---|
| Nickel (Ni) | 24.0 – 26.0 |
| Chromium (Cr) | 19.0 – 21.0 |
| Molybdenum (Mo) | 6.0 – 7.0 |
| Copper (Cu) | 0.5 – 1.5 |
| Nitrogen (N) | 0.15 – 0.25 |
| Carbon (C) | 0.02 max |
| Manganese (Mn) | 2.0 max |
| Phosphorus (P) | 0.03 max |
| Sulfur (S) | 0.01 max |
| Silicon (Si) | 0.5 max |
| Iron (Fe) | Balance |
Incoloy Alloy 25-6MO features a fully austenitic structure, which is crucial for its high corrosion resistance and mechanical strength. The austenitic phase, stabilized by the high nickel content, provides excellent ductility and toughness, even at low temperatures.
The carefully engineered composition of Incoloy Alloy 25-6MO ensures superior performance in aggressive environments. The high levels of nickel, chromium, and molybdenum make it particularly effective in resisting pitting, crevice corrosion, and stress corrosion cracking, especially in chloride-containing environments. The addition of copper and nitrogen further enhances its resistance to various acids and improves its mechanical properties.
This balance of excellent corrosion resistance, mechanical strength, and formability makes Incoloy Alloy 25-6MO a cost-effective alternative to higher nickel alloys, suitable for a wide range of industrial applications.
Incoloy Alloy 25-6MO (UNS N08926) is known for its exceptional mechanical and physical properties, making it ideal for tough industrial applications. These properties ensure the alloy’s durability and performance under extreme conditions.
Tensile strength measures how much tension the alloy can handle before breaking. In its annealed state, Incoloy Alloy 25-6MO has a tensile strength ranging from 90-120 ksi (620-827 MPa). For even higher strength, heat treatment can increase it to at least 190 ksi (1034 MPa).
Yield strength indicates the stress level at which the alloy starts to deform permanently, with a value of 48 ksi (330 MPa) in its annealed state. Additionally, the alloy has an elongation of 42%, meaning it can stretch significantly before breaking. This combination of properties ensures that the material maintains its shape and structural integrity under high stress while allowing for significant deformation without cracking.
The hardness of Incoloy Alloy 25-6MO (Rb 86) means it can resist wear and tear, making it perfect for abrasive conditions like those in heavy machinery. This property reflects the alloy’s resistance to indentation and wear, ensuring its longevity in demanding environments.
Incoloy Alloy 25-6MO has a density of 8.03 g/cm³, making it strong yet not overly heavy. Its modulus of elasticity is 188 GPa, ensuring it remains stiff under stress. The modulus of rigidity, or shear modulus, is 71 GPa, which is crucial for applications involving torsional stress. The alloy also exhibits good thermal stability and conductivity. Its coefficient of thermal expansion is 9.26 µin/in-°F (16.7 µm/m-°C) between 25-600°C (70-1100°F), ensuring dimensional stability across a wide temperature range. Additionally, the electrical resistivity of 31.4 µohm-in (80.0 µohm-cm) and thermal conductivity of 11.5 W/m-°C (79.8 Btu-in/ft²-hr-°F) make it suitable for high-temperature applications and effective heat transfer.
The mechanical and physical properties of Incoloy Alloy 25-6MO make it a versatile and reliable material for a wide range of industrial applications. Its strength, ductility, and resistance to thermal and mechanical stress ensure its performance in demanding environments.
INCOLOY Alloy 25-6MO (UNS N08926) is celebrated for its outstanding corrosion resistance, ideal for use in harsh environments. This exceptional durability stems from its unique chemical composition and fully austenitic structure, which provide robust defense against various types of corrosion.
The alloy’s high molybdenum content (6.0 – 7.0%) and the presence of nitrogen (0.15 – 0.25%) significantly enhance its resistance to pitting and crevice corrosion. These forms of localized corrosion are particularly problematic in environments containing chloride ions, such as marine and chemical processing settings. INCOLOY Alloy 25-6MO demonstrates excellent performance in these conditions, with high temperatures at which pitting and crevice corrosion begin. The Pitting Resistance Equivalent Number (PREN) for this alloy is 47, indicating its high resistance to pitting.
The alloy exhibits outstanding resistance to both oxidizing and non-oxidizing acids. The high chromium content (19.0 – 21.0%) forms a passive oxide layer on the surface, protecting the alloy from attack by oxidizing acids. Simultaneously, the combination of molybdenum and copper (0.5 – 1.5%) enhances its resistance to non-oxidizing acids, such as sulfuric and phosphoric acids. As a result, INCOLOY Alloy 25-6MO is highly suitable for handling aggressive chemicals in various industrial applications.
Stress corrosion cracking (SCC) is a critical concern in environments with high tensile stress and the presence of chlorides. The high nickel content (24.0 – 26.0%) in INCOLOY Alloy 25-6MO plays a crucial role in enhancing its resistance to SCC. The alloy’s fully austenitic structure, stabilized by nickel, provides excellent toughness and ductility, further contributing to its resistance to this form of corrosion. Compared to lower nickel alloys, such as AISI 317, INCOLOY Alloy 25-6MO offers superior performance in chloride-rich environments.
In addition to its resistance to localized and stress corrosion, INCOLOY Alloy 25-6MO offers excellent general corrosion resistance. This is due to the synergistic effect of its alloying elements, which collectively provide a robust defense against a wide range of corrosive media. The balanced composition ensures that the alloy remains stable and maintains its integrity even in highly aggressive environments.
The exceptional corrosion resistance of INCOLOY Alloy 25-6MO makes it ideal for various demanding applications, including:
INCOLOY Alloy 25-6MO’s corrosion resistance properties make it a versatile and reliable material for industries requiring durable and long-lasting solutions.
INCOLOY Alloy 25-6MO is ideal for marine and offshore environments due to its superior resistance to chloride-induced corrosion and seawater. This makes it perfect for seawater cooling systems, desalination equipment, and offshore platforms. Its ability to withstand pitting and crevice corrosion ensures long-term reliability in seawater cooling applications. In desalination plants, particularly in evaporators and heat exchangers, the alloy’s high resistance to the corrosive effects of seawater and brine is invaluable. Offshore platforms benefit from the alloy’s robustness against harsh marine conditions, ensuring structural integrity and longevity.
In chemical processing, INCOLOY Alloy 25-6MO excels due to its resistance to corrosive chemicals, making it perfect for caustic chloride systems, sulfuric and phosphoric acid environments, and heat exchangers in facilities like refineries and chemical plants. The alloy’s resistance to stress corrosion cracking and pitting is crucial for handling aggressive chloride solutions. In sulfuric and phosphoric acid environments, the presence of molybdenum and copper enhances its resistance, making it ideal for storage tanks, piping, and reactors.
In the oil and gas sector, INCOLOY Alloy 25-6MO is valued for its durability and resistance to corrosive fluids, making it ideal for downhole well screens, equipment, wirelines, and slicklines. The alloy’s high resistance to stress corrosion cracking and pitting makes it suitable for downhole applications where exposure to corrosive fluids is common. Components like wirelines and slicklines benefit from the alloy’s strength and resistance to harsh well environments, enhancing operational reliability.
INCOLOY Alloy 25-6MO is employed in the food processing industry due to its compliance with food-grade standards and high corrosion resistance. Its resistance to various food acids and cleaning chemicals ensures hygiene and longevity of equipment such as mixing tanks, conveyors, and piping.
The pulp and paper industry uses INCOLOY Alloy 25-6MO for its resistance to aggressive chemicals in bleaching processes, making it suitable for bleach plants and pulp digesters. The alloy is used in bleach washers, drums, and pipelines where exposure to chlorine dioxide and other bleaching agents is prevalent, ensuring durability and resistance to the corrosive chemicals involved in the pulping process.
Power generation relies on INCOLOY Alloy 25-6MO for its high-temperature and corrosion resistance, especially in condenser tubing, service water piping, and feedwater heaters. The alloy’s resistance to corrosive effluents and high thermal conductivity make it suitable for condensers. It ensures reliability and longevity in handling high-temperature and corrosive water streams.
The versatility of INCOLOY Alloy 25-6MO extends to various other industrial applications. It is used in air pollution control systems due to its resistance to corrosive gases, making it suitable for components in flue gas desulfurization units and other pollution control equipment. In salt plant evaporators, the alloy’s resistance to high salinity and corrosive conditions is essential. Additionally, it provides durability and resistance to corrosive flue gases in industrial chimneys as stack liners.
INCOLOY Alloy 25-6MO’s exceptional properties make it a preferred material for numerous applications across diverse industries, ensuring performance and reliability in the most demanding environments.
In the chemical processing industry, Incoloy Alloy 25-6MO is utilized for its exceptional resistance to various corrosive chemicals. It is ideal for equipment handling non-oxidizing acids such as sulfuric and phosphoric acids, as well as in caustic chloride systems. Applications include reaction containers for drugs, resin production equipment, and piping systems that require robust materials to withstand aggressive chemical environments.
Incoloy Alloy 25-6MO is extensively used in the oil and gas industry due to its superior resistance to corrosive fluids and environments, making it ideal for marine and offshore platform equipment, downhole well screens, and service water piping. Its resilience ensures reliability in harsh operational conditions, extending the lifespan of critical components.
The power generation industry benefits from Incoloy Alloy 25-6MO’s resistance to high temperatures and corrosive environments, making it ideal for condenser tubing, service water piping, and feedwater heaters. This ensures reliable performance and longevity in power plants, where durability is crucial.
In the pulp and paper industry, Incoloy Alloy 25-6MO is essential for equipment in bleaching processes due to its resistance to aggressive chemicals like chlorine dioxide. It is used in bleach washers, drums, pipelines, and other equipment exposed to harsh bleaching agents, ensuring operational efficiency and durability.
In marine and offshore applications, Incoloy Alloy 25-6MO is employed in seawater desalination devices, seawater heat exchangers, and various marine engineering systems. Its high resistance to chloride-induced corrosion makes it suitable for use in brackish water and seawater environments, ensuring durability and reliability.
In the food processing industry, Incoloy Alloy 25-6MO is used in equipment where high corrosion resistance is essential. It is applied in food-grade machinery, including mixing tanks, conveyors, and piping systems, ensuring hygiene and longevity in environments exposed to food acids and cleaning chemicals.
Incoloy Alloy 25-6MO is also used in nuclear power generation due to its ability to handle corrosive environments. Its robust properties make it suitable for various components in nuclear power plants, ensuring safety and performance in critical applications.
Air pollution control systems benefit from the use of Incoloy Alloy 25-6MO in components where acid condensates can form and cause pitting and crevice corrosion. The alloy is employed in stack liners, outlet ducts, and other systems requiring resistance to corrosive gases and acidic environments.
Incoloy Alloy 25-6MO’s versatility extends to various industrial applications, including heat exchangers, pipes, springs, fire fighting systems, and hydraulic and perfusion piping. It offers a cost-effective alternative to higher nickel alloys in many aggressive environments, ensuring reliable performance and longevity.
In marine environments, Incoloy Alloy 25-6MO significantly reduced maintenance and enhanced reliability in seawater cooling systems on offshore platforms. Its superior resistance to chloride-induced corrosion ensured long-term performance even in highly saline conditions. Similarly, in chemical processing applications, the alloy’s exceptional resistance to sulfuric and phosphoric acids minimized downtime and maintenance costs. This dual advantage of corrosion resistance and cost savings highlights the alloy’s overall effectiveness in demanding environments.
In the pulp and paper industry, Incoloy Alloy 25-6MO has proven invaluable in harsh bleaching environments where chlorine dioxide is used. The alloy’s resistance to these aggressive conditions ensures consistent performance and reduces the frequency of equipment replacements. As a result, plants experience fewer production interruptions, leading to increased operational efficiency and significant cost savings.
In the oil and gas sector, Incoloy Alloy 25-6MO is used in downhole applications. It withstands corrosive fluids and high temperatures, ensuring reliable operation. The alloy’s resistance to stress corrosion cracking and pitting enhances durability and reduces failures compared to conventional materials. This leads to improved operational safety and lower operational costs for operators.
In power generation, Incoloy Alloy 25-6MO has demonstrated its worth in condenser tubing and feedwater heaters. In a power plant, the alloy handled corrosive effluents and high-temperature steam, resulting in extended service life and improved efficiency of heat exchange systems. The plant observed a significant decrease in maintenance requirements and an overall increase in operational reliability.
Incoloy Alloy 25-6MO has been effectively used in air pollution control systems, particularly in components exposed to acidic condensates. In a flue gas desulfurization unit, the alloy resisted pitting and crevice corrosion, ensuring the longevity of stack liners and outlet ducts. This performance reduced maintenance intervals and helped maintain compliance with stringent environmental regulations.
Desalination plants have also benefited from Incoloy Alloy 25-6MO, particularly in evaporators and heat exchangers. The alloy’s resistance to the corrosive effects of seawater and brine resulted in fewer equipment failures and lower maintenance costs. This contributed to the operational stability and efficiency of large-scale desalination facilities.
Overall, Incoloy Alloy 25-6MO’s exceptional resistance to corrosion and high durability make it a valuable material across multiple demanding industries. Its use ensures efficiency, safety, and cost savings, solidifying its role as a reliable choice for various challenging applications.
Machining INCOLOY® Alloy 25-6MO requires specific considerations due to its high strength and corrosion-resistant properties. The alloy can be machined using conventional methods, but adjustments are necessary to optimize performance and tool life.
Using carbide tools, the recommended cutting speeds range from 10 to 50 feet per minute. These speeds help manage heat generation and tool wear, which are crucial for maintaining machining efficiency and accuracy.
Careful control of depth of cut and feed rates helps manage heat buildup and tool wear, ensuring smooth cutting and extending tool life.
INCOLOY® Alloy 25-6MO is highly weldable using various conventional welding processes. However, specific techniques and filler materials are recommended to maintain its corrosion-resistant properties.
GTAW (TIG welding) offers precise control, ideal for thin sections and critical joints. It is recommended for achieving high-quality welds with minimal defects.
GMAW (MIG welding) is efficient for welding thicker sections of INCOLOY® Alloy 25-6MO. This process allows for higher deposition rates, making it suitable for large-scale fabrication.
SMAW, commonly known as stick welding, is versatile and can be used in various positions. It is effective for welding INCOLOY® Alloy 25-6MO in field applications where other welding processes may be impractical.
SAW is ideal for welding thick sections and long weld seams. The process provides deep penetration and high deposition rates, making it efficient for industrial applications involving INCOLOY® Alloy 25-6MO.
PAW offers precise control over the welding arc and is suitable for high-quality welds. It is particularly effective for welding thin sections of INCOLOY® Alloy 25-6MO, ensuring minimal distortion and high weld integrity.
Using appropriate filler metals is crucial for maintaining corrosion resistance; higher molybdenum-containing filler metals like INCONEL® 625, INCONEL® C-276, and INCO-WELD® 686CPT® are recommended.
Post-weld heat treatment (PWHT) may be necessary to relieve residual stresses and improve the mechanical properties of the weld. The specific PWHT parameters should be determined based on the application and service conditions to achieve the desired properties.
Proper machining and welding techniques are essential for fabricating INCOLOY® Alloy 25-6MO components. Following recommended practices and using appropriate filler metals ensure the alloy’s integrity and corrosion resistance, leading to reliable performance in demanding industrial applications.
Below are answers to some frequently asked questions:
Incoloy Alloy 25-6MO (UNS N08926) has a chemical composition that includes Nickel (Ni) 24.0-26.0%, Chromium (Cr) 19.0-21.0%, Molybdenum (Mo) 6.0-7.0%, Copper (Cu) 0.5-1.5%, Nitrogen (N) 0.15-0.25%, Carbon (C) max 0.02%, Manganese (Mn) max 2.0%, Phosphorus (P) max 0.03%, Sulfur (S) max 0.01%, Silicon (Si) max 0.5%, and the remainder being Iron (Fe). This composition provides the alloy with excellent corrosion resistance and mechanical properties suitable for various demanding applications.
Incoloy Alloy 25-6MO (UNS N08926) exhibits excellent mechanical properties, including a tensile strength of 689 MPa (100 ksi) and a yield strength of 331 MPa (48 ksi) in the annealed condition. It has an elongation at break of at least 42% and a hardness measured at 86 on the Rockwell B scale. The modulus of elasticity is 188 GPa, and it has a Poisson’s ratio of 0.33. The alloy’s density is approximately 8.03 g/cm³. These properties, combined with good workability and weldability, make it suitable for demanding applications requiring high strength and corrosion resistance.
Incoloy Alloy 25-6MO resists corrosion due to its high molybdenum (6%) and nitrogen (0.2%) content, which provide excellent resistance to pitting and crevice corrosion, especially in chloride-rich environments. Additionally, its substantial nickel (around 25%) and chromium (approximately 20%) levels contribute to overall corrosion resistance and thermal stability. The presence of copper enhances its performance in non-oxidizing acids like sulfuric acid. These properties make Incoloy Alloy 25-6MO suitable for harsh environments such as marine, chemical processing, and desalination applications, as discussed earlier in the article.
Incoloy Alloy 25-6MO (UNS N08926) is commonly used in various applications due to its exceptional corrosion resistance and mechanical properties. It is employed in marine and offshore platform equipment, chemical processing equipment like desalination plants and air pollution control systems, power industry components such as condenser tubing and feedwater heaters, and food and pulp processing facilities. Additionally, it is used in heat exchangers, pipes, and other equipment requiring high corrosion resistance, as well as in oil and gas industry applications like wirelines and downhole well screens. This versatility makes it a preferred choice in multiple industries facing corrosive environments.
Incoloy Alloy 25-6MO can be machined using standard techniques with considerations for its high hardness and strength, such as lower speeds, rigid tooling, and optimal lubrication. For welding, it is readily weldable using methods like GMAW, GTAW, SMAW, SAW, and PAW, with filler metals typically made from INCONEL alloys. Proper techniques include a larger root opening and aggressive torch manipulation to minimize base metal dilution. Post-welding, stress relieving or annealing at temperatures over 1175°C can restore the alloy’s properties, ensuring effective machining and welding while maintaining its superior corrosion resistance.
Incoloy Alloy 25-6MO (UNS N08926) is commonly used in several industries due to its exceptional corrosion resistance and mechanical properties. Key industries include chemical processing, where it resists non-oxidizing acids; oil and gas, particularly for marine and offshore platform equipment; nuclear power generation, for components in aggressive environments; food processing, complying with food-grade standards; pulp and paper, especially in bleaching plants; marine and offshore applications like desalination equipment; and air pollution control systems, where it prevents acid condensate corrosion. These diverse applications highlight its versatility and reliability in harsh conditions.
