Influence of Aluminum Content on Mechanical Properties and Cold Workability of Fe-33Ni-15Co Alloy

The influence of 0.01% to 0.25% of Aluminum content (in mass percent) on the mechanical properties and cold workability of low thermal expansion Fe-33Ni-15Co sheets in the annealed and hot rolled condition was investigated. Addition of Al up to 0.15% resulted in the increase of ductility and toughness and improvement of workability. Besides, achievement of fine grain structure and increase in the amount of annealing twins caused ductility to improve. Addition of Al higher than 0.15% led to the increase in oxidation reaction during melting process and to refine under argon atmosphere. This caused the volume fraction of Al containing inclusions to increase and consequently the ductility and toughness to decrease.