Let HY-industry take you to Invar alloy world
（HY industry- Technical Center internal data）
Origin information of Invar alloy:
Invar, also known as “invariant steel”, commonly known as Invar in Chinese, is a kind of nickel steel alloy, which is a special steel containing 36% nickel. Because of its small expansion coefficient, it is suitable for measuring components.Invar is a transliteration of the French word “Invar”.
First discovered by the Swiss physicist C. E. Guillaume in 1896.
Invar is an iron-based high-nickel alloy, usually containing 32%-36% nickel, and also contains a small amount of S, P, C and other elements, the rest is about 60% of Fe, because nickel is expanding austenite, so High nickel changes the transformation of austenite to martensite to below room temperature, ˉ100～ˉ120°C. Therefore, after annealing, Invar has a face-centered lattice structure at a temperature range below room temperature and below room temperature. The austenite structure is also a solid solution in which nickel is dissolved in γ-Fe, and thus Invar has the following properties.
Small expansion coefficient:
Invar’s average expansion coefficient is generally 1.5 × °C, nickel is 36% to 1.8 × °C, and does not change at room temperature ˉ 80 ° C – + 100 ° C.
Strength and hardness are not high:
The carbon content of Invar is less than 0.05%, the hardness and strength are not high, the tensile strength is about 517Mpa, the yield strength is about 276Mpa, and the Vickers hardness is about 160. Generally, the strength can be improved by cold deformation, while the strength is increased. Still have good plasticity.
Low thermal conductivity:
Invar alloy has a thermal conductivity of 0.026 to 0.032 cal/cm•sec•°C, which is only 1/3-1/4 of the thermal conductivity of 45# steel.
High plasticity and toughness:
The elongation and section shrinkage and impact toughness of Invar are high, the elongation δ = 25-35%, impact toughness αK = kg • m / cm
Most metals and alloys expand in volume when heated, and volume shrinks when cooled. However, due to its ferromagnetism, Invar has an abnormal thermal expansion due to the effect of the tile in a certain temperature range, and its expansion coefficient is extremely low. Sometimes it’s even zero or negative.
In 1896, the Swiss Swiss scientist Giovin discovered a wonderful alloy. The alloy has a significant decrease in the coefficient of thermal expansion near the Curie point, and the so-called abnormal thermal expansion (negative anomaly), which can be very close to room temperature. In the wide temperature range, a small or even near-zero expansion coefficient is obtained. The composition of this alloy is 64% Fe and 36% Ni, which is a face-centered cubic structure with a grade of 4J36(Invar36). Its Chinese name is Yin. Steel, the English name is invar, meaning the same volume. This remarkable alloy contributed so much to the advancement of science that its discoverer (Swiss physicist Guillaume) won the Nobel Prize in Physics in 1920 for this, and he was the first and only scientist in history. Received this honor for a metallurgical achievement.
It is mainly used for glass sealing alloys in which electrical components are matched with hard glass, soft glass and ceramic. It is a low expansion alloy. Its state is both hard and soft. 4J36(Invar 36/K93600/1.3912) Invar/glass sealant has a low expansion coefficient and good plasticity in the temperature range of ˉ60°～ˉ80°, which is used to make the size near constant in the temperature range. Components, widely used in radio, precision instruments, instruments and other industries, 4J36 (Invar 36/K93600/1.3912) Invar/glass seal alloy used to make standard measuring tools, microwave resonators, bimetallic passive layers,LNG cavity etc .
Invar (invar ingot )is mainly used to manufacture standard rulers, thermometers, range finder, clock balance, block gauge, cavity of microwave equipment, gravimeter components, thermal bimetal component materials, optical instrument parts, etc. Manufactured by melt method.
In the more than 100 years since the advent of Invar, the application field with low low expansion coefficient has been rapidly expanded. The precision instrumentation made of Invar, the pendulum of the standard clock, the balance wheel and the spring of the clock have become early The most important product. In the 1920s, the replacement of platinum with Invar as a guide wire for glass sealing greatly reduced the cost. By the 1950s and 1960s, the use of Invar alloy continued to expand, mainly for radio tubes and thermostats. In the 1980s to the 1990s, it was widely used in microwave technology, liquid gas storage containers, color TVs, shadowless steel strips, and overhead power transmission core materials. , Vibration chamber, laser collimator cavity, three steps to repeat the camera substrate at this moment. After entering the 21st century, with the rapid development of space technology. New applications include space-based remote sensors, precision lasers, optical measurement systems and waveguides for structural components, microscopes, support systems for large lenses in astronomical telescopes, and a variety of scientific instruments that require lenses.
with Invar is constantly used in satellites, lasers, ring laser gyroscopes and other advanced high-tech products. And move towards a higher level.
HY-industry is a long-term supplier of Baosteel Group. It develops the workshop production process of Invar materials, successfully supplies LNG shiphouse materials, and the French astronomical telescope project. It also has orders from countries such as the United States and Germany.