Abstract: Improved wrought 7xxx aluminum alloy products are disclosed. The improved wrought 7xxx aluminum alloy products generally include 6.0-10.0 wt. % Zn, 1.4-2.2 wt. % Mg, 1.3-2.5 wt. % Cu and 0.080-0.250 wt. % Cr. The improved wrought 7xxx aluminum alloy products generally have a thickness of from 3.0 inches to 12 inches, and realize an improved combination of properties, such an improved combination of crack deviation resistance, strength, fracture toughness and corrosion resistance.

Abstract: A production line method of resistance welding comprising the steps of contacting a metal sheet with an electrode having an initial contact surface area at a force to provide a pressure to the metal sheet; applying a current though the electrode to the metal sheet; measuring dimensional changes of the electrode; correlating dimensional changes in the electrode to changes in the initial contact surface area; and adjusting the force to compensate for the changes in the initial contact surface area of the electrode to maintain pressure to the metal sheet. The force may be adjusted by stepping the force to maintain pressure to the faying surface of the metal sheet to be welded. By maintaining the pressure at the faying surface the life cycle of the electrodes may be increased without forming discrepant welds.

Abstract: The present invention provides a production line method of resistance welding comprising the steps of contacting a metal sheet with an electrode having an initial contact surface area at a force provide a pressure to the metal sheet; applying a current though the electrode to the metal sheet; measuring dimensional changes of the electrode; correlating dimensional changes in the electrode to changes in the initial contact surface area; and adjusting the force to compensate for the changes in the initial contact surface area of the electrode to maintain pressure to the metal sheet. The force may be adjusted by stepping the force to maintain pressure to the flaying surface of the metal sheet to be welded. By maintaining the pressure at the faying surface the life cycle of the electrodes may be increased without forming discrepant welds.

Abstract: A method of resistance welding comprising the steps of contacting a metal sheet with an electrode having an initial contact surface area at a force to provide a pressure to the metal sheet applying a current through the electrode to the metal sheet; measuring dimensional changes of the electrode; correlating dimensional changes in the electrode to changes in the initial contact surface area; and adjusting the force to compensate for the changes in the initial contact surface area of the electrode to maintain pressure to the metal sheet. The force may be adjusted by stepping the force to maintain pressure to the faying surface of the metal sheet to be welded. By maintaining the pressure at the faying surface the life cycle of the electrodes may be increased without forming discrepant welds. The current may also be stepped to further extend electrode life.