A horizontal band saw should do that. I used to use one for cutting steel pipe back in my bike-building days. The speed should be slow enough to prevent any heating of the metal, but if you're prepared to hang around you can always dribble cutting oil over it as it goes to help dissipate the heat. Clamping an aluminium heat sink to the blade as close as possible to the cut point might help reduce the speed at which heat builds up.
