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What is Invar 36?

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Author : LZH
Update time : 2023-08-04 17:49:01
What is Invar 36?
Invar 36 or Fe-36wt% Ni alloy is known for its nearly zero coefficient of thermal expansion (CTE) below its Curie temperature (230 ºC). Due to its dimensional invariance over a wide range of service temperatures, Invar 36 alloy is widely used in components that require high dimensional stability, high reliability, and high precision, including length standard rulers, clock parts, television shadow-mask frames, liquefied natural gas storage tanks, gyroscopes, satellite remote sensing equipment, astronomical telescope bases, etc. However, its intrinsic microstructural characteristic, i.e., a single face-centered cubic (FCC) solid solution, results in relatively low hardness and strength, although it gives rise to excellent ductility; for conventionally manufactured Invar 36, their room temperature 0.2% yield strength is in between 230 and 350 MPa and tensile strength in between 400 and 500 MPa. The low yield strength greatly restricts its application as a load-bearing structural material in space and aerospace industries. Its high work hardening and high flexibility also make it challenging to machine Invar 36 alloy into complex-shaped components.

Influence of addition of TiAl particles on microstructural and mechanical property development in Invar 36 processed by laser powder bed fusion
Nonconventional manufacturing methods such as additive manufacturing (AM) were recently employed to process Invar 36. AM is well known for its outstanding near-net-shape manufacturing capability, which would be ideal for manufacturing Invar 36 components for various applications. It was reported that Invar 36 fabricated by laser powder bed fusion (L-PBF) or direct laser deposition (DLD) showed unanimously high room temperature YS of 350–400 MPa, with horizontally built samples showing slightly better YS than vertically built samples due to the presence of columnar grains. As such, the AM-processed Invar 36 shows slightly enhanced YS compared to the conventionally manufactured counterpart, whose YS usually falls between 230 MPa and 350 MPa, thanks to the development of fine cell structures in the former. The CTE of AM-processed Invar 36 with high density/good structural integrity below 200 °C is usually between 1 × 10−6 and 2 × 10−6 K−1, comparable to the conventionally manufactured counterpart. Thus, It is concluded that AM is beneficial for enhancing the YS of Invar 36 while maintaining CTE. Nonetheless, there is still much room for improving YS in Invar 36 for applications as a structural material.

C, V, Mo, Cr were widely added into Invar 36
Conventionally, elements such as C, V, Mo, and Cr were widely added into Invar 36, which, in combination with proper heat treatments, could lead to the formation of carbides or carbonitrides such as VC, TiC, V(C, N), Ti(C, N) that could enhance yield strength (YS) and ultimate tensile strength (UTS). Other metallic elements such as Be, Ti, Al, and Sn were added to strengthen Invar 36 by producing Ni3Be, Ni3(Ti, Al), and other intermetallic compounds through aging treatments. While the strengths of Invar 36 could be enhanced to some extent by introducing the above alloying elements, the alloy's thermal expansion properties and flexibility were generally degraded. CTE usually increased with the addition of the above alloying elements because the addition resulted in more or less consumption of Ni from the γ matrix, causing deviation of Ni content from the ideal 36 wt% levels in the matrix, which gives rise to the strongest spontaneous volume magnetostriction effect and thus the lowest CTE in Fe-Ni alloys. Moreover, with the conventional manufacturing method being used to introduce the above alloying elements, it usually requires complex processes to produce homogeneously distributed precipitates in the matrix of Invar 36. This usually involves casting, cold/thermo-mechanical processing, annealing treatment, aging treatment, etc., which is time-consuming and expensive. Also, to make these materials into components, massive machining is needed.

Price of Invar 36
Invar 36 particle size and purity will affect the product's Price, and the purchase volume can also affect the cost of Invar 36. A large amount of large amount will be lower. The Price of Invar 36 is on our company's official website.

Invar 36 supplier
Luoyang Tongrun Nano Technology Co. Ltd.  (TRUNNANO) Luoyang City, Henan Province, China, is a reliable and high-quality global chemical material supplier and manufacturer. It has more than 12 years of experience providing ultra-high quality chemicals and nanotechnology materials, including Invar 36, nitride powder, graphite powder, sulfide powder, and 3D printing powder. If you are looking for high-quality and cost-effective Invar 36, you are welcome to contact us or inquire at any time.
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