A weldable, high magnesium-content aluminum-magnesium alloy consisting essentially of at lest 5 to 6% by weight magnesium (Mg), 0.05 to 0.15% by weight zirconium (Zr), 0.7 to 1% by weight manganese (Mn), 0.01 to 0.2% by weight titanium (Ti), 0.005 to 0.5% by weight cerium (Ce), 0.05 to 0.5% by weight of one or more elements selected from the scandium group of the Periodic Table and/or terbium (Tb), wherein at least scandium (Sc) is included with or without terbium (Tb) and with or without 0.05 to 0.45% by weight of an element from the lanthanide series, the balance being aluminum (Al), and unavoidable contaminants not exceeding 0.2% by weight silicon (Si).