Adhesive bonding process for aluminum alloy bodies including hypophosphorous acid anodizing

An adhesive bonding process for making vehicle structures wherein a surface portion of an aluminum alloy body is anodized in an aqueous solution of hypophosphorous acid (H3PO2) to form an anodic oxide coating. A layer of adhesive is applied onto the surface portion and the adhesive coated anodized surface portion is joined to an adjacent metal structure. The phosphorous acid anodizing is preferably carried out for less than 1 minute at about 5-40 volts and a current density of about 1-50 mA/cm2 in a solution containing about 1-25 wt % hypophosphorous acid. Anodization time is more preferably about 10-30 seconds and is about 20 seconds in a particularly preferred embodiment.