The role of controlled expansion alloys

Expansion alloy is a kind of precision alloy with abnormal thermal expansion characteristics, also known as thermal expansion alloy, which is widely used in the fields of electronics industry, precision measuring tools, precision instruments and low temperature engineering. General metals and alloys expand when heated, and the amount of expansion increases linearly with the increase of temperature, but the thermal expansion curve of some alloys has a bending point at a certain temperature, and the thermal expansion coefficient below the bending point is lower than the normal thermal expansion coefficient above the bending point. Much more, this phenomenon is called anomalous thermal expansion characteristics.

Low expansion alloys are mostly used in components that require approximately constant dimensions at a certain ambient temperature. Mainly include: (1) precision instruments, components in optical instruments, such as arms of precision balances, pendulum rods of standard parts, balance wheels, external compensation of clocks, etc.; (2) length scales. Geodetic baseline ruler; (3) Various resonant cavities, waveguides for microwave communication, standard frequency generators, etc.; (4) Blades and support rods of standard capacitors; (5) Liquid natural gas, liquid hydrogen, liquid oxygen, etc. Storage tanks and transport pipes; (6) passive layers of thermal bimetals; (7) shadow masks in high-resolution cathode ray tubes (picture tubes); (8) molds for composite parts in the aerospace industry; (9) For satellites, lasers, ring laser gyroscopes and other advanced high-tech products.

Due to the high nickel content of the low-expansion alloy, the hardenability and hardenability of the steel are improved, and the gas resistance, corrosion resistance and wear resistance of the steel are improved. Through the analysis of the chemical composition, metallographic structure, mechanical and physical properties of the low-expansion alloy, the machinability of the low-expansion alloy is similar to that of the austenitic stainless steel, but it is more difficult to process than the austenitic stainless steel. It mainly has the characteristics of large cutting force, high cutting temperature, and fast tool wear. Therefore, in the process of processing, the low-expansion alloy appears soft, sticky, and has great plasticity, the chip is not easy to break, and the friction between the chip and the front surface is increased. The wear of the tool is aggravated, which not only reduces the durability of the tool, but also reduces the machining accuracy of the workpiece. Therefore, when machining low-expansion alloys, high-performance carbide-coated tools and new machining methods must be used to achieve To make the cutting process go smoothly, as long as the method is correct, the difficult-to-machine low-expansion alloys can be easily machined.