Shanghai Fortune Alloy Co.,Ltd
A precision alloy with abnormal thermal expansion, also known as thermal expansion alloy, is widely used in the fields of electronic industry, precision measuring tools, precision instruments and cryogenic engineering. The general metal and alloy expands when heated, and the expansion increases linearly with the temperature, but the thermal expansion curve of some alloys appears at a certain temperature bending point (different slope of the intersection of the tangent of two segments, as the TK in the figure shows, the thermal expansion coefficient below the bending point is much lower than the normal thermal expansion coefficient above the bending point, which is known as abnormal thermal expansion.
Expansion alloy is divided into low expansion alloy and fixed expansion alloy, which is also called sealing alloy. The average expansion coefficient below the bending point of the low expansion alloy is lower than that of the 3 X 10-6 Shan-1, and the average expansion coefficient of the fixed expansion alloy below the bending point is about ($number) X10-6 Shan-1. The main expansion alloys are NI series, Fe-Ni system and Fe-Ni series alloy, and the high chromium steel and CO-FE CRE series alloys are also used as expansion alloys, but the dosage is not large. In addition to the specific thermal expansion coefficient, the expansion alloy is also required to have good sealing, weldability, corrosion resistance, machinability and machinability, and it is not allowed to have a phase transition with obvious change in the temperature range. The chemical composition of the alloy must be controlled accurately during the manufacturing process, and its products are generally rods, plates, strip, wire and tubing.
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