FIELD: steel manufacturing.
SUBSTANCE: group of inventions includes a method for manufacturing a preliminarily coated steel billet (1), a method for manufacturing a welded billet, a method for manufacturing a press-hardened steel part, a pre-coated steel billet (variants), a welded billet and a press-hardened part. In the manufacture of a pre-coated steel billet, a pre-coated steel strip (2) having a steel substrate (3) with preliminary coating (5) applied on at least one side is fed. The specified preliminary coating (5) contains a layer (9) of an intermetallic alloy and a metal layer (11) continuing over said layer (9) of an intermetallic alloy, while the metal layer (11) is an aluminium layer, an aluminium alloy layer or an alloy layer based on aluminium. Laser cutting of said pre-coated steel strip (2) is performed to obtain at least one preliminarily coated steel billet (1). Preliminarily coated steel billet (1) has a laser cut edge (13), which contains a substrate section (14) and a preliminary coating section (15). Laser cutting is carried out in such a way that the area (14) of the substrate located on the formed edge (13) of the laser cut has oxygen content greater than or equal to 15% by weight.
EFFECT: method makes it possible to perform laser cutting of preliminarily coated steel billets in such a way that aluminium contamination is easily removed from the laser cut edge during subsequent brushing, allows laser welding of said preliminarily coated steel blanks without cleaning the laser cut edge before welding, while the resulting weld seam has good mechanical strength and toughness.
26 cl, 12 dwg, 2 tbl
