It seems that using ferromagnetic materials is the easiest way to shield static magnetic field. But is it still working in strong field strength(up to 5T)? Another question is that are mu-metal (iron-nickle) shield under magnetic force in the field? I didn't see anyone considering this. Is it because the force is too small?
Iron is a ferromagnetic material and it begins to saturate at 1.6 teslas so if "dipped" into a 5T static field it will be far less effective as a shield.
There will be a force on all ferromagnetic materials in a static magnetic field.