Abstract: A method for fusion welding of one or more steel sheets (1, 2) made of press-hardened steel, preferably manganese-boron steel is disclosed. At least one of the steel sheets has a metallic coating (4) which contains aluminum, and the fusion welding is performed while filler material (11) is being fed into the molten bath (9). In order to improve the hardenability of the weld seam (14), irrespective of whether the steel sheets to be welded together are steel sheets of the same or different material grades and/or steel sheets of different sheet thicknesses, a single laser focal spot (16) with different energy distribution is generated on the molten bath by means of one or more optical elements such that the laser focal spot (16) has a smaller laser focal spot area (16.1) and a larger laser focal spot area (16.2).

Abstract: A method for laser beam welding of one or more steel sheets made of press-hardenable manganese-boron steel is disclosed. At least one of the steel sheets has a coating of aluminium. The laser beam welding takes place by feeding an additional wire into a melt bath generated by of a laser beam. The additional wire contains at least one austenite-stabilising alloy element. The weld seam after hot forming (press hardening) has a strength that is comparable to the base material. The laser beam is put into oscillation such that it oscillates transverse to the welding direction, wherein the oscillation frequency of the laser beam is at least 200 Hz, preferably at least 500 Hz. The method dispenses with removing the aluminum coating at the edge of the sheet-metal edges to be welded.

Abstract: A method and a device for fusion welding one or more steel sheets made of press-hardenable steel, preferably manganese-boron steel; are disclosed. In the method, the fusion welding is performed by supplying filler wire into a molten bath generated a laser beam. In order to improve the hardenability of the weld seam, regardless of whether the steel sheets to be welded to one another are steel sheets of identical or different material quality, the filler wire is coated with graphite particles prior to fusion welding and the filler wire coated in this manner is introduced directly into the molten bath in such a way that the tip of the filler wire melts in the molten bath, the graphite particles are mixed with a waxy or liquid carrier medium to be applied to the filler wire, and the mixture is applied in the form of a coating to the filler wire. The method and the corresponding device are distinguished by a high productivity and a relatively low energy consumption.

Abstract: A method for producing a tailor-made semi-finished sheet metal product where two steel sheets of different material grades and/or thicknesses are joined by laser welding. At least one of the sheets is press-hardenable steel having a metallic coating of aluminium or aluminium-silicon. Filler wire is fed into the weld melt. The filler wire is substantially free of aluminium and contains at least one alloy element which promotes the formation of austenite in a content that is at least 0.1 wt. % greater than that in the press-hardenable steel. The filler wire is heated before being fed into the weld melt. The steel sheets have a gap delimited by the edges of the sheets having an average width of at least 0.15 mm. The ratio of the volume of filler wire inserted into the gap to the volume of the steel sheet material melted by the laser beam is at least 20%.

Abstract: A method for producing a tailor-made semi-finished sheet metal product where two steel sheets of different material grades and/or thicknesses are joined by laser welding. At least one of the sheets is press-hardenable steel having a metallic coating of aluminium or aluminium-silicon. Filler wire is fed into the weld melt. The filler wire is substantially free of aluminium and contains at least one alloy element which promotes the formation of austenite in a content that is at least 0.1 wt. % greater than that in the press-hardenable steel. The filler wire is heated before being fed into the weld melt. The steel sheets have a gap delimited by the edges of the sheets having an average width of at least 0.15 mm. The ratio of the volume of filler wire inserted into the gap to the volume of the steel sheet material melted by the laser beam is at least 20%.

Abstract: A method for laser welding one or more workpieces made of press-hardenable steel in a butt joint, wherein the workpiece or workpieces have a thickness of between 0.5 and 1.8 mm, and/or a jump in thickness of between 0.2 and 0.4 mm occurs at the butt joint, and wherein laser welding is carried out with the feed of filler wire into the molten bath, which is generated only by at least one laser beam. The filler wire contains at least one alloy element from the group comprising manganese, chromium, molybdenum, silicon and/or nickel, which alloy element promotes the formation of austenite in the molten bath generated by the laser beam, wherein said at least one alloy element is present in the filler wire in a mass percentage greater by at least 0.1 wt. % than in the steel of the workpiece or workpieces and the workpiece or workpieces used are non-coated or the coating thereof is partially removed.

Abstract: A method for laser welding one or more workpieces made of press-hardenable steel in a butt joint, wherein the workpiece or workpieces have a thickness of between 0.5 and 1.8 mm, and/or a jump in thickness of between 0.2 and 0.4 mm occurs at the butt joint, and wherein laser welding is carried out with the feed of filler wire into the molten bath, which is generated only by at least one laser beam. The filler wire contains at least one alloy element from the group comprising manganese, chromium, molybdenum, silicon and/or nickel, which alloy element promotes the formation of austenite in the molten bath generated by the laser beam, wherein said at least one alloy element is present in the filler wire in a mass percentage greater by at least 0.1 wt.% than in the steel of the workpiece or workpieces and the workpiece or workpieces used are non-coated or the coating thereof is partially removed.

Abstract: A method includes producing sheet steel products, in which steel blanks or steel strips of different thicknesses and/or material grades are welded together along a joint formed by edges of the steel blanks or steel strips. In order that the welding seam of such a sheet steel product does not lose the hardened microstructure obtained by abrupt cooling during warm forming with heating to an austenization temperature, before the welding process, a viscous liquid, such as a paste, or a solid, pulverulent, or aerosol-like substance that contains at least one component that increases the strength of the weld seam that is to be produced, is applied to at least one weld edge of the steel blanks or steel strips that are to be welded together.