4J36 has special low expansion iron and nickel alloy with ultra-low expansion coefficient. The Curie point of alloy is 230 ℃, lower than 230 ℃ alloy is ferromagnetic, higher than 230 ℃ is nonmagnetic, the alloy is mainly used for the components of near and constant in temperature change, widely used in wireless point industry, precision instruments, instruments and so on. There is extremely low thermal expansion coefficient between - 250 ℃ and + 200 ℃. Good plasticity and toughness.