how does ferromagnetic substance become a permanent magnet?

A ferromagnetic substance is a substance in which the magnetic moments of the individual atoms are aligned and point in the same direction. These substances are strongly magnetized when placed in an external magnetic field. Ferromagnetic materials can be further classified as hard ferromagnets and soft ferromagnets. Hard ferromagnetic materials are those which do not lose their magnetism even when external magnetic field has been removed. Examples include Alnico, which is an alloy of iron, aluminum, nickel, cobalt, and copper. In soft ferromagnetic materials, the magnetism disappears on removal of external magnetic field. Hence only hard ferromagnets can be used to make permanent magnets.  Ferromagnetic materials can be converted into permanent magnets in the following ways:

1. A conventional method of making a permanent magnet from an iron bar is to hold it in the north south direction and beat it repeatedly.
2.  It can also be done by stroking where an existing magnet is moved from one end of the material to the other in the same direction. 
3. An efficient way to make a permanent magnet is to place a ferromagnetic material in a solenoid and pass current. The magnetic field of the solenoid magnetizes the rod.
4. The industrial method to manufacture permanent magnets is to heat the ferromagnetic material above its Curie temperature, allowing it to cool in a magnetic field and then hammering it as it cools.