Grade: 4J29 4J44

    Standard: YB/T  5231-2005

A precision alloy with abnormal thermal expansion properties, also known as thermal expansion alloy, is widely used in the electronics industry, precision measuring instruments, precision instruments, and cryogenic engineering. Expansion alloys are divided into low-expansion alloys and fixed-expanded alloys, which are also known as sealing joints. Expansion alloys mainly include Fe-Ni, Fe-Ni-Co and Fe-Ni-Cr alloys. In addition to a specific thermal expansion coefficient, the expanded alloy also requires good sealing properties, weldability, corrosion resistance, workability, and free-machining properties depending on the application, and does not allow the expansion characteristics to be caused within the use temperature range. Obviously changed phase change. The expansion alloy must accurately control the chemical composition of the alloy during the manufacturing process. Its products are generally bars, plates, strips, wires and pipes.

1.KOVAR|ASTM F15|K94610|Nilo K |FeNi29Co17

Grade: 4J29 4J44

Standard: YB/T  5231-2005



1.Kovar alloy has been used for making hermetic seals with the harder Pyrex glasses and ceramic materials.

2.This alloy has found wide application in power tubes, microwave tubes, transistors and diodes. In intergrated circuits, it has been used for the flat pack and the dual-in-line package.


1).Alloy grades and chemical composition consistent with the provisions


2).Alloy average linear expansion coefficient in line


2.Ceramvar alloy

Grade: 4J33、4J34(YB/T5234-1993)

Standard : ASTM F1466, (Fe-Ni27-Co25), Chinese 4J33/4J34


1)Relative Grade:


2)Grade & Chemical Composition 


1.Under condition that the average coefficient of the linear expansion meets the requirements of the standard, the content of nickel and cobalt are allowed to deviate from the stated range.

2.The shape and dimensions of the alloys are in compliance with GB/T14985.


3)Alloy average linear expansion coefficient in line


3.Invar alloy,ASTM F1684,UNS k93600 (FeNi36),Chinese 4J36


A Nickel-Iron, low expansion alloy containing 36% Nickel. It maintains nearly constant dimensions over the range of normal atmospheric temperatures and has a low coefficient of expansion from cryogenic temperatures to about +500°C. Nilo 36 also retains good strength and toughness at cryogenic temperatures. 

Applications include standards of length, thermostat rods, laser components and tanks and piping for the storage and transportation of liquefied gasses.


1).Relative Grade:


2).Grade & Chemical Composition 


3.Alloy average linear expansion coefficient in line

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