The material covered by this specification is intended for use in the manufacture of machined parts in which it is necessary to have little change in size with temperature change. The low expansivity characteristics of this material are applicable over a limited range of temperatures. The most useful range is up to the inflection temperature which is at approximately 390° F. The mean coefficient of expansion between 32° F and the inflection temperature is approximately 1.4 × 10−⁶ per ° F. If a lower coefficient of expansion is necessary in the above temperature range, bars should be ordered cold drawn, annealed and quenched, or in special cases quenched and stabilized.