ORGANIC COATED ALUMINUM ALLOY SHEET EXCELLENT IN SPOT RESISTANCE WELDABILITY AND CORROSION RESISTANCE AND SPOT RESISTANCE WELDING METHOD USING THE SAME

摘要

PURPOSE: To obtain an aluminum alloy sheet improved in continuous spotting properties at the time of spot resistance welding, excellent in corrosion resistance and easily and economically producible on an industrial scale. ;CONSTITUTION: As pretreatment, an alumina layer on the surface is removed away by alkali etching treatment, or, in an acidic aq. soln. contg. mineral acid, mainly, a magensia layer is removed away. Otherwise, two treatments are successively executed, and as for the aluminum allay sheet in which the oxidized film has been subjected to the etching treatment, respectively, as primary layers, a chromate film is formed on the welding joint face at the time of spot resistance welding by the chromium coating weight of 5 to 200mg/m² expressed in terms of metal chromium, and a chromate film is fomred on the face with which an electrode chip is to be contacted by the chromium coating weight of 5 to 100mg/m² expressed in terms of metal chromium and by ≤75% of the chromium coating weight in the welding joint face. Moreover, the surface is coated with organic resin as a secondary layer by 0.01 to 3.0μm as a dry film thickness.;COPYRIGHT: (C)1995,JPO