Coated steel sheet and method and apparatus for its fabrication

摘要

A steel sheet is endowed with a coating made up of a principal layer of zinc-chrome alloy, of which the preponderant phase presents a delta and/or gamma structure. The coating also incorporates a underlying adherence layer of zinc-chrome alloy, inserted between the steel of the sheet and the principal layer that presents:- a) a centred cubic crystalline structure of the lambda type; b) a balanced chrome content sufficiently elevated to obtain this lambda structure; and c) a junction at least partially epitaxial with the steel. A method and installations for the fabrication of steel sheets coated with an alloy of two metal elements are also claimed, in which the coating is deposited under vacuum during the continuous defiling of the steel sheet successively in front of sources of the two metal elements.