INFLUENCE OF BILLET STRUCTURE OF THE QUALITY OF STAMPED HEAVY-DUTY SEMIFINISHED PRODUCTS FABRICATED FROM THE AL-ZN-MG-CU-ZR SYSTEM

The structure of a continuously cast ingot that is used as a billet fo r producing a shaped semifinished product to a great extent controls t he quality of the deformed metal: the better the casting quality, the less deformation is necessary to produce maximized properties for the alloys. For highly alloyed multiphase alloys that solidify over a wide temperature range, the fine grain structure is particularly important for maintaining improved ingot density which occurs as the crystal gr owth region is restricted. To a great extent, the ingot structure typi fies the grain internal condition, i.e., the dimensions of the dendrit ic branches or the dendrite parameter. In particular, the dendrite bra nch dimensions control the level of secondary phase distribution, the nature of liquation, and the dendritic porosity, which have a direct i nfluence on the structure and properties of deformed semifinished prod ucts.