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Imagine an alloy with remarkable magnetic properties that can revolutionize the performance of electronic devices, transformers, and magnetic shields. The UNS K94840 Iron-Nickel Alloy, renowned for its unique chemical composition and exceptional properties, stands as a cornerstone in advanced manufacturing and engineering applications. In this article, we delve into the intricate details of its composition, uncover the secrets behind its magnetic prowess, and explore the diverse applications that benefit from its capabilities. Whether you’re an engineer, researcher, or manufacturer, understanding the full potential of UNS K94840 could be the key to unlocking innovative solutions in your field. What makes this alloy so special, and how can it be harnessed to its full potential? Let’s find out.
UNS K94840, also known as Type 2 magnetic alloy, is an iron-nickel alloy with a specific chemical composition that enhances its performance in various applications. This alloy primarily consists of iron and nickel, with additional elements in smaller quantities to improve specific properties.
The chemical composition of UNS K94840 is as follows:
| Element | Weight Percentage |
|---|---|
| Iron (Fe) | 48.2 to 53% |
| Nickel (Ni) | 47 to 49% |
| Manganese (Mn) | 0 to 0.8% |
| Silicon (Si) | 0 to 0.5% |
| Cobalt (Co) | 0 to 0.5% |
| Chromium (Cr) | 0 to 0.3% |
| Molybdenum (Mo) | 0 to 0.3% |
| Copper (Cu) | 0 to 0.3% |
| Carbon (C) | 0 to 0.050% |
| Sulfur (S) | 0 to 0.030% |
| Phosphorus (P) | 0 to 0.010% |
The high nickel and iron content gives UNS K94840 excellent magnetic properties, making it ideal for use in transformers and electronic devices. The specific balance of elements ensures that the alloy meets the stringent requirements for high-performance magnetic applications.
The presence of other elements like manganese, silicon, and cobalt, even in small quantities, contributes to the alloy’s stability and durability. Manganese increases the alloy’s strength and hardness, while silicon boosts its magnetic properties. Cobalt, although minimal, enhances the magnetic characteristics and thermal stability of the alloy.
Overall, the precise balance of elements in UNS K94840 ensures it meets the demanding requirements for high-performance magnetic applications, making it a top choice in various industrial and technological fields.
The saturation flux density of UNS K94840 defines the maximum magnetic flux the material can handle before becoming saturated. UNS K94840 has a saturation induction of approximately 15,000 Gauss at an applied field of 100 Oersteds, ensuring it can maintain magnetic performance even under high fields. This high saturation flux density makes the alloy suitable for high-performance applications requiring efficient magnetic properties.
Magnetic permeability measures how easily a material supports the formation of a magnetic field. UNS K94840 exhibits excellent magnetic permeability, ranging from 10,500 to 15,000 at 40 Gauss (4 mT) initially, and achieving maximum values up to 150,000. This high permeability ensures minimal core losses and high magnetic efficiency, making it ideal for applications where magnetic performance is critical.
The coercive force is the magnetic field strength needed to reduce the material’s magnetization to zero after saturation. UNS K94840 has a low coercive force, between 0.05 and 0.07 Oersteds, indicating it can be easily magnetized and demagnetized. This property is essential for applications requiring rapid changes in magnetization.
Residual magnetism, or remanence, refers to the remaining magnetization in the material after the external magnetic field is removed. UNS K94840 has a residual magnetism of around 9,000 Gauss. This characteristic is significant for applications where a certain level of magnetization must be retained, such as in magnetic shielding and specific sensor types.
The combination of high saturation flux density, excellent magnetic permeability, low coercive force, and significant residual magnetism makes UNS K94840 a versatile and efficient material for various magnetic applications. These properties enable the alloy to perform exceptionally well in demanding environments, such as cores of instrument transformers, magnetic shields, and other electronic devices. The ability to maintain high magnetic performance with minimal energy loss is crucial for the efficiency and reliability of these applications.
AMS 7718, ASTM A753, MIL-N-14411, and IEC 404-8-6 are standards that ensure the quality and performance of wrought nickel-iron soft magnetic alloys like UNS K94840. These standards cover chemical composition, mechanical properties, and magnetic characteristics.
AMS 7718 specifies the requirements for wrought nickel-iron soft magnetic alloys, including UNS K94840, covering aspects like chemical composition, mechanical properties, and magnetic characteristics. Compliance with AMS 7718 ensures that UNS K94840 meets the necessary quality and performance standards for use in high-precision magnetic applications.
ASTM A753 addresses wrought nickel-iron soft magnetic alloys, detailing chemical composition, magnetic properties, and heat treatment processes to ensure optimal performance. This standard ensures that the alloy has the correct balance of elements and meets the required magnetic properties for various applications, such as transformer laminations and rotating machinery laminations.
MIL-N-14411 covers nickel-iron soft magnetic alloys for military use, specifying chemical and mechanical properties, as well as magnetic characteristics to meet stringent military standards. This ensures the alloy’s performance and reliability in demanding military applications.
IEC 404-8-6 is an international standard for soft magnetic materials, including nickel-iron alloys like UNS K94840. It provides guidelines for magnetic performance, testing methods, and applications to ensure the alloy’s suitability for high-performance magnetic components. This standard ensures consistent performance across different industrial and technological applications.
UNS K94840 is commonly used to make laminated cores for electrical devices. The alloy’s excellent magnetic properties help these cores efficiently manage changing magnetic fields with little energy loss. This makes it ideal for use in transformers, inductors, and reactors, particularly in high-frequency applications.
In instrument transformers, UNS K94840 is valued for its magnetic properties, which are crucial for accurate measurement and signal processing. Its high saturation flux density and low core loss make it perfect for precision applications where maintaining magnetic performance under varying loads is essential.
UNS K94840’s outstanding magnetic shielding abilities make it a top choice for protecting sensitive electronics from interference. Its high permeability effectively blocks and redirects magnetic fields, ensuring the smooth operation of devices like medical imaging equipment and aerospace electronics.
The alloy is also used in various electronic devices that require high magnetic efficiency. UNS K94840’s ability to maintain high permeability at low magnetizing forces makes it suitable for cores of inductors, transformers, and sensors within electronic circuits. This ensures reliable and efficient performance under different operating conditions.
UNS K94840 is highly precise and reliable, making it ideal for stepper motors in watches and timing devices. The alloy’s magnetic properties allow for precise control of motor movements, ensuring accurate positioning and timing, which is critical for the functionality of these precision instruments.
In the gas industry, UNS K94840 is used for safety caps due to its durability and magnetic properties. The alloy’s resistance to harsh environmental conditions and its ability to maintain magnetic performance make it suitable for safety-critical applications, ensuring the safe operation of gas equipment.
The alloy finds applications in aeronautical engineering, particularly in hyper-frequency oscillators used in communication systems. UNS K94840’s high magnetic permeability and stability under varying temperatures make it ideal for these high-frequency components, ensuring efficient and reliable communication in aerospace environments.
UNS K94840 is used in magnetic sensors for current, angular position, and displacement sensing. The alloy’s low coercive force and high permeability allow for precise detection and measurement of magnetic fields, making it suitable for automotive, industrial automation, and consumer electronics applications where accurate and reliable measurements are essential.
The manufacturing process of UNS K94840 involves several crucial steps to ensure the alloy meets high-quality and performance standards.
The process begins with the careful selection of raw materials, followed by melting in vacuum induction furnaces to prevent contamination and ensure purity. Once melted, the alloy is cast into ingots or billets, which are then subjected to hot working processes such as forging, rolling, and extrusion to form the desired shapes and sizes. Cold working processes, including drawing and cold rolling, may also be employed to achieve precise dimensions and further enhance the mechanical properties.
Heat treatment plays a vital role in optimizing the mechanical and magnetic properties of UNS K94840. The specific heat treatment processes include stress relieving, annealing, and magnetic annealing.
Stress relieving is done to reduce residual stresses from manufacturing processes like cold working. This involves heating the alloy to 800-1600°F (427-871°C) and cooling it slowly, which minimizes distortion and improves dimensional stability.
Annealing improves the ductility and reduces the hardness of the alloy. The alloy is heated to 1300-2200°F (704-1204°C) and then cooled at a controlled rate. This process recrystallizes the grain structure, eliminates internal stresses, and enhances the magnetic properties.
Magnetic annealing enhances the alloy’s magnetic properties. The alloy is heated to 1450-2050°F (788-1121°C) in a hydrogen atmosphere, which improves magnetic permeability, reduces core losses, and enhances remnant flux. Controlled cooling prevents stress formation and ensures optimal magnetic performance.
The combination of precise manufacturing and tailored heat treatment processes ensures that UNS K94840 exhibits superior mechanical and magnetic properties. Properly treated UNS K94840 demonstrates high magnetic permeability, low coercive force, and excellent saturation flux density. These properties are essential for applications in high-performance magnetic components, including instrument transformers, magnetic shields, and electronic devices.
The ability to fine-tune the alloy’s properties through controlled manufacturing and heat treatment processes makes UNS K94840 a versatile material for various industrial applications.
Alloy 4750 (UNS K94840) typically comprises about 48% nickel and 52% iron, which grants it one of the highest saturation flux densities among nickel-iron alloys.
NILO Alloy 36 (UNS K93600) and NILO Alloy 42 (UNS K94100) contain 36% and 42% nickel, respectively, with the remainder being iron. Both are known for their low thermal expansion coefficients.
NILO Alloy 48 (UNS K94800) also contains about 48% nickel and 52% iron but is primarily used for glass-to-metal seals due to its specific thermal expansion properties.
Magnetic Properties:
Thermal Expansion:
Alloy 4750 (UNS K94840):
Laminated cores for instrument transformers
Magnetic shields
Cores for electronic and communication devices
NILO Alloy 36 (UNS K93600):
Tooling for aerospace composites
Standards of length and precision components
Cryogenic engineering
NILO Alloy 42 (UNS K94100):
Thermostat rods
Semiconductor lead frames
Thermostatic bi-metal strips
NILO Alloy 48 (UNS K94800):
Glass-to-metal seals
Thermostats in industrial applications up to 450°C (840°F)
Alloy 4750 (UNS K94840):
NILO Alloys (36, 42, 48):
Alloy 4750 (UNS K94840) is best utilized in applications requiring high magnetic performance, such as magnetic cores and shields in electronic and communication devices.
NILO Alloy 36 (UNS K93600) is highly valued in aerospace and cryogenic engineering due to its low thermal expansion properties.
NILO Alloy 42 (UNS K94100) is preferred in semiconductor and thermostatic applications for its consistent thermal expansion.
NILO Alloy 48 (UNS K94800) finds its niche in glass-to-metal seals and industrial thermostats, where its specific thermal expansion properties are advantageous.
Below are answers to some frequently asked questions:
The chemical composition of UNS K94840 Iron-Nickel Alloy consists primarily of Nickel (47.0 to 49.0%) and Iron (balance, approximately 48.2 to 53%). It also includes small amounts of Carbon (maximum 0.05%), Manganese (maximum 0.8%), Silicon (maximum 0.5%), Phosphorus (maximum 0.03%), Sulfur (maximum 0.01%), Cobalt (maximum 0.30%), Molybdenum (maximum 0.30%), and Copper (maximum 0.30%). This specific composition is crucial for its performance, particularly its magnetic properties, making it suitable for applications requiring high permeability and low coercive force.
The key magnetic properties of UNS K94840 Iron-Nickel Alloy include a high saturation flux density of approximately 16,000 gauss (1.6 tesla), high magnetic permeability, and varying coercive force based on annealing treatments, ranging from 0.85 Oersteds down to 0.05 Oersteds at higher annealing temperatures. Additionally, the remnant flux density varies from 6,300 gauss to 10,900 gauss depending on the annealing process. The Curie temperature of the alloy is between 840°F and 930°F (449°C to 499°C), above which it loses its magnetic properties. These characteristics make it suitable for various magnetic applications.
The UNS K94840 Iron-Nickel Alloy is used in a variety of applications due to its high magnetic permeability, low core loss, and high saturation flux density. Typical applications include laminated cores for instrument transformers, magnetic shields, and cores for electronic and communications devices. It is also used in audio-related transformers, magnetic amplifiers, transducers, radar pulse transformers, synchronous motors, torque motors, loading coils, and radiofrequency shields. Additionally, the alloy is employed in temperature compensators for its stable magnetic properties across a range of temperatures.
UNS K94840 Iron-Nickel Alloy complies with several standards and specifications, including AMS 7718, ASTM A753, MIL-N-14411, and IEC 404-8-6. These standards outline requirements for chemical composition, mechanical properties, and magnetic characteristics, ensuring the alloy’s suitability for various applications such as laminated cores, instrument transformers, magnetic shields, and electronic devices.
UNS K94840 Iron-Nickel Alloy, also known as Alloy 4750 or High Perm 49, is manufactured through various wrought processes, typically in forms such as bar, wire, sheet, and strip. It undergoes cold-rolling and annealing to achieve desired magnetic properties. Heat treatment is crucial for optimizing its magnetic characteristics, with processes like mill process anneal and high-temperature hydrogen anneal significantly enhancing properties such as remnant flux density and coercive force. The alloy must meet standards like AMS 7718 and ASTM A753, ensuring quality through chemical analysis and magnetic evaluation.
UNS K94840 compares with other nickel-iron alloys primarily through its high saturation flux density, which makes it ideal for magnetic applications like laminated cores and magnetic shields. Unlike Permalloy, which has a higher nickel content and excels in high permeability and low hysteresis loss applications, UNS K94840 is favored for its robust magnetic performance. It also differs from low-expansion nickel alloys that are used for their stable dimensions over temperature changes. Thus, UNS K94840’s unique properties and compliance with standards make it particularly suited for electronic and communication device components.
