Which Material is Chosen for a Transformer Core, and Why?

A material with higher permeability and less conductivity is chosen for the transformer core.
High permeability so that it can easily allow the magnetic field through it and low conductivity
so that the strength of Eddy current is less and hence losses are less.

Such material is steel , it is ferromagnetic material and has high permeability, but it also has
good conductivity hence to decrease the conductivity 4- 5 % of silicon is added to it , hence
the main material is called silicon steel.

There is a certain process called cold rolled grain orientation through which the direction of
grains edge is made parallel to the direction of magnetisation , hence the permeability further
increases .

Hence now a days CRGO STEEL is used as transformer core .