Fe-Ni alloy with 36% nickel has a very low expansion coefficient and is called Invar because its size hardly changes with temperature. The strength and hardness of Invar alloy are not high, and the tensile strength is generally less than 500MPa. In order to improve the strength of Invar alloys, Invar alloy systems such as Fe-Ni-C, Fe-Ni-Mn-C, Fe-Ni-Co, etc. have been developed. Although the increase of the element addition can increase the strength of the body alloy, the expansion performance of the alloy also increases. Therefore, while obtaining the strength of Invar alloy through element adjustment, it is also necessary to take into account the index of low expansion coefficient. In addition, this type of alloy can only exert its performance advantages after heat treatment.

The domestic grade corresponding to Invar alloy is 4J36 alloy, which contains 35.0%~37.0% Ni and the rest is Fe. 4J36 alloy has the characteristics of small thermal expansion coefficient, good dimensional stability, and easy demagnetization. Therefore, it has been widely used in aerospace, military weapons, microwave communications, color TV shadow masks, and petroleum transportation containers. It has become a favorite in the 21st century. One of the alloys of interest, and has been continuously developed in applications. For this reason, in view of the composition and performance requirements of 4J36 alloy used in a special industry in China, by studying the influence of the composition and annealing temperature during heat treatment on the alloy performance, it provides a basis for the optimization of the composition and heat treatment process of 4J36 alloy for special working conditions. .