Abstract: The invention relates to a manufacturing process for an aluminum block of at least 250 mm thick designed for the manufacture of elements for vacuum chambers in which the following operations are carried out successively: an alloy block is cast by semi-continuous casting, the composition of this block in weight % being: Si 0.5-1.5; Mg: 0.5-1.5; Fe<0.3; Cu<0.2; Mn<0.8; Cr<0.10; Ti<0.15, other elements <0.05 each and <0.15 in total, the rest aluminum; solution heat treatment is performed at a temperature ranging between 450 and 560° C. directly on the cast block and optionally homogenized; the block that has undergone solution heat treatment is quenched at a cooling speed between the solution heat treatment temperature and 200° C. of at least 200° C./h; the block quenched and optionally stress-relieved is artificially aged.