METHOD OF LASER WELDING FOR PRODUCING A SEMI-FINISHED SHEET OF HARDENABLE STEEL WITH A COATING OF ALUMINIUM OR ALUMINIUM-SILICON BASE

摘要

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%.