Method for adhering reinforcing patches during superplastic forming

This invention pertains to superplastic forming of two or more layers of sheet metal. More specifically this invention relates to a method for locating and temporarily bonding a sheet metal reinforcement piece to a larger sheet metal blank so that the sheet metal blank and reinforcing sheet can be deformed together in the same elevated temperature stretch forming operation. A method is disclosed for temporarily bonding reinforcing sheet metal pieces or other metal pieces to a sheet metal blank for forming at an elevated temperature such as is employed in superplastic forming of suitable aluminum, magnesium, stainless steel or titanium alloys. The pieces are bonded to the blank in locations in which the piece will acquire a desired shape from co-formation with the blank. Suitable water suspendible sodium silicate compositions, such as water glass bond the piece to the blank during high temperature forming and permit removal after forming.