Super Invar Alloy Annealing and Heat Treating
Annealing Super Invar
Heat the Super 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 Super Invar for Lowest Thermal Expansion and Optimum Stability
For the lowest thermal expansion and optimum stability, the recommended heat treating method for Super Invar Alloy is to heat at 1550°F (843°C) for 1 hour, water quench, followed by a stress relieving operation at 600°F (316°) for 1 hour, air cool and age at 200°F (93°C) for 24 hours, then air cool.
Because Super Invar Alloy oxidizes readily at heat treating temperatures above about 1000°F (538°C), it is recommended that parts be heat treated in a protective environment (e.g. vacuum, hydrogen, dissociated ammonia, or inert gases).