What happens when molten metal cools within a strong magnetic field? I don't know what more say, don't remember anything relevant to this in my uni text books.
If the metal is magnetic, like iron, chromium and some others, the atoms will be orient themselves to the magnetic filed, resulting solid material which will be magnetic. The opposite phenomena explains why magnets loses their magnetism when heated (not nescessarily to their melting point) as well; the atoms gets to higher energy states and will realign themselves randomly.
If the molten metal is not magnetic, the material will of course not be magnetic after the magnetic field is removed, but I guess there are properties that can be affected anyway, maybe the resulting material more easily could form crystals when it becames solid, and therefore could be slightly stronger in some directions, but also more brittle. Maybe.