4J32 is a typical low-expansion alloy, also known as Super-Invar alloy. 4J32 low expansion alloy has a very low expansion coefficient in the range of atmospheric temperature change (-60-80℃). It has good plasticity, stable performance and poor thermal conductivity. It is mainly used in the manufacture of precision parts with highly accurate size within the range of ambient temperature changes and precision instruments, instrument devices, resonator parts and thermal bimetal passive layers requiring constant size and very low expansion coefficient near room temperature, and other radio frequency components with small scale drift with temperature changes, standard scales, astronomical instrument frames and clock balance wheels and other devices.

The chemical composition of 4J32 low expansion alloy should be strictly controlled when used, and its organizational stability should be strictly checked according to the use temperature of the parts. When the alloy composition is deviated, different degrees of austenite (y) will change to acicular martensite (a) at normal and low temperatures. During phase transformation, the expansion coefficient of the alloy increases correspondingly with the volume expansion effect. 4J32 has high nickel content, good plasticity, and good corrosion resistance in atmosphere, seawater and fresh water.