Invar Alloy Annealing Heat Treating
(Also know as Invar 36, NILO 36, Pernifer 36, and Invar Steel)
Heat the Invar Alloy to 1450°F (790°C) and hold heat for 30 minutes per inch of thickness then air cool. Heating to temperatures above 1000°F (538°C) relieves the presence of cold work stresses. The higher the temperature used, the lower the annealed hardness will be.
Heat Treating Invar for Lowest Optimal Dimensional Stability
For the optimal dimensional stability, the recommended heat treating method for Invar Alloy is to heat at 1500°F (815°C) for 30 minutes per inch of thickness, water quench and reheat to 600°F (316°) for 1 hour, followed by air cooling.