A steel sheet is provided. The steel sheet includes a multilayer coating including at least one zinc-based layer being 0.1% to 20% magnesium by weight which is covered by a fine temporary protective layer of 5 to 100 nm. The fine temporary protective layer is composed of metal or metal oxide selected from the group consisting of aluminum, chromium, aluminum oxides AlOx, with x being strictly between 0.01 and 1.5 and chromium oxides CrOy, with y being strictly between 0.01 and 1.5. The at least one zinc-based layer is not alloyed with the temporary protective layer. Manufacturing methods for a sheet and part are also provided.

A steel sheet is provided. The steel sheet includes a multilayer coating including at least one zinc-based layer being 0.1% to 20% magnesium by weight which is covered by a fine temporary protective layer of 5 to 100 nm. The fine temporary protective layer is composed of metal or metal oxide selected from the group consisting of aluminum, chromium, aluminum oxides AlOx, with x being strictly between 0.01 and 1.5 and chromium oxides CrOy, with y being strictly between 0.01 and 1.5. The at least one zinc-based layer is not alloyed with the temporary protective layer. Manufacturing methods for a sheet and part are also provided.

The present invention provides a mold method for surface treatment of aluminum component comprising: providing straightening and rounding the aluminum component; the scraping pretreatment; the oxidation prevention and lubrication of scraping; the precise scraping of the aluminum rod. The present invention enables on-line high precision shape finishing and surface cleaning of the aluminum component which satisfies the processing requirement of providing uniformity and consistent treatment by the subsequent extrusion processing as part of the production line in order to produce high quality aluminum, aluminum alloy, aluminum bimetallic and multi-metallic composite profiles and special profiles.