Invar 42 is a unique alloy with exceptional properties that make it ideal for various applications in the precision engineering industry. This nickel-iron alloy is known for its low thermal expansion coefficient, high dimensional stability, and excellent resistance to corrosion and oxidation. In this article, we will delve into the details of Invar 42, its chemical composition, mechanical properties, standards, specifications, and applications.
Anton Metal and the Development of Invar 42
Invar 42 was developed by Anton Metal Corporation, a company founded in 1916 in New York City. Anton Metal specialized in the production of precision alloys, including Invar, an alloy composed of nickel and iron with a very low coefficient of thermal expansion. Invar was first discovered by Charles Edouard Guillaume, a French physicist, in 1896, and it quickly gained popularity in scientific and industrial applications due to its exceptional stability over a wide temperature range.
In the 1930s, Anton Metal expanded its product line to include new alloys that combined the desirable properties of Invar with other metals. One such alloy was Invar 42, which was created by adding small amounts of silicon and manganese to Invar. The resulting alloy had even lower thermal expansion than Invar, making it ideal for precision instruments and devices that require high dimensional stability over a wide temperature range.
Chemical Composition of Invar 42
Invar 42 is a nickel-iron alloy composed of 41% nickel and 59% iron, with small amounts of silicon (0.3%) and manganese (0.5%). The addition of silicon and manganese improves the alloy’s strength and ductility, as well as its resistance to stress relaxation and thermal cycling. Invar 42 also has a low carbon content, typically less than 0.05%, which contributes to its excellent resistance to corrosion and oxidation.
Mechanical Properties of Invar 42
Invar 42 has a unique combination of mechanical properties that make it ideal for precision engineering applications. Its low coefficient of thermal expansion (CTE) means that it expands very little when heated, making it ideal for applications where dimensional stability is critical. The CTE of Invar 42 is approximately 1.1 × 10^-6 /°C, which is lower than that of Invar (1.2 × 10^-6 /°C) and most other materials.
In addition to its low CTE, Invar 42 has excellent strength and ductility, as well as good fatigue resistance. Its tensile strength ranges from 600 MPa to 800 MPa, depending on the heat treatment, and its elongation at break is typically around 30%. Invar 42 also has excellent resistance to stress relaxation, which is the gradual loss of tension in a material over time due to creep or plastic deformation.
Standards and Specifications for Invar 42
Invar 42 is widely used in the precision engineering industry and is available in various forms, including bars, sheets, plates, and wire. The alloy is specified by several standards organizations, including ASTM International, DIN, and JIS. Some of the commonly used specifications for Invar 42 are listed below:
ASTM F1684 – Standard Specification for Iron-Nickel-Cobalt Sealing Alloy DIN 17745 – Wrought Nickel-Iron-Cobalt Low Expansion Alloys JIS G4318 – Stainless Steel Wire Rods for Welding Filler Metals
Applications of Invar 42
Invar 42 finds extensive use in the precision engineering industry, where dimensional stability and accuracy are critical. The alloy’s low thermal expansion and high dimensional stability make it ideal for various applications, including:
- Aerospace and Defense: Invar 42 is used in satellite structures, microwave cavity resonators, and other aerospace applications that require high dimensional stability over a wide temperature range.
- Electronics: Invar 42 is used in electronic packaging, semiconductor fabrication, and other applications where dimensional stability is critical for accurate performance.
- Tooling and Dies: Invar 42 is used in tooling and dies for molding, stamping, and other precision manufacturing processes to ensure accurate and consistent results.
- Scientific Instruments: Invar 42 is used in scientific instruments such as interferometers, spectrometers, and telescopes, where high accuracy and stability are essential.
- Medical Devices: Invar 42 is used in medical devices such as X-ray equipment and MRI machines, where high dimensional stability is necessary for accurate imaging.
Conclusion
Invar 42 is a unique alloy with exceptional properties that make it ideal for various applications in the precision engineering industry. Its low coefficient of thermal expansion, high dimensional stability, and excellent resistance to corrosion and oxidation make it ideal for applications where accuracy and stability are critical. Invar 42 has found extensive use
Post time: May-27-2023
