BATTERY BOX BOTTOM PART FOR ELECTRIC VEHICLES

The present invention is directed to a bottom part of a battery box for electric or hybrid motor vehicles made from an aluminium alloy sheet having a thickness between 2 and 6 mm, wherein said aluminum alloy comprises 2.5 to 4.0 wt. % of Mg, 0.1 to 0.8 wt. % of Mn, 0.4 wt. % or less of Si, 0.5 wt. % or less of Fe, 0.5 wt. % or less of Cu, 0.1 wt. % or less of Cr, 0.1 wt. % or less of Zn, 0.1 wt. % or less of Ti, rest aluminium and unavoidable impurities up to 0.05 wt. % each and 0.15 wt. % total. Another object of the invention is a method to make a bottom part of battery box according to the invention comprising casting said aluminium alloy into a rolling ingot; homogenizing and/or reheating said rolling ingot; hot rolling and optionally cold rolling said rolling ingot to obtain a sheet with a thickness between 2 mm and 6 mm. The bottom part of battery box of the invention is simultaneously light, resistant against intrusion, sufficiently formable and leak tight, corrosion resistant, able to accommodate temperature variations and sufficiently stiff and strong.