why transformer core never behave like as a magnet?

In transformer, a coil is wound on core and primary coil is connected to power supply.
According to physics:- when we wound conducting wire (copper) on any magnetic material in the form of coil, and then the terminals of coil is connected to power supply.
Then material behave like a magnet.
Same case happen in transformer, then
why transformer core never work like as magnet?