Welding electrode for sheets of aluminum or steel, and method for producing the electrode

An electrode for welding metal sheets made from steel and aluminum or aluminum alloys, comprising:

• an alloy being comprised of:
• chromium in a proportion greater than or equal to 0.1% and less than 0.4% by weight,
• zirconium in a proportion between 0.02 and 0.04% by weight,
• phosphorus in a proportion of less than 0.015% by weight,
• copper and
• unavoidable impurities in a proportion of less than 0.1% by weight,
• wherein electrical conductibility of said electrode being greater than or equal to 90% IACS (International Annealed Copper Standard) and
• wherein structure of said electrode comprises incoherent chromium precipitates, more than 90% of which have a projected surface smaller than 1 μm2, said incoherent chromium precipitates having dimensions at least between 10 and 50 nm,
• wherein said electrode further having a fiber structure, visible along a cross-section of the active face of said electrode after surfacing and chemical etching, said structure being comprised of a plurality of radial fibers, said fibers having a thickness of less than 1 mm, and a central zone without fiber structure having a diameter of less than 5 mm.