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Abstract

A method is provided for repairing by solid state diffusion a damaged portion of an inner surface of a hole of a metal part. The method comprises machining the hole to a cylindrical diameter sufficient to remove the damaged portion therefrom and provide a new hole with a smooth finish into which a metal bushing is inserted, the outer diameter being of size and finish relative to the machined diameter of the hole to provide a close fit therewith, the composition of the metal bushing being compatible with that of the metal part. A cylindrical metal mandrel of diameter corresponding to the inner diameter of the bushing is inserted into the bushing to provide an assembly thereof with the metal part, the metal mandrel having a mean coefficient of thermal expansion greater than that of the metal bushing for a selected solid state diffusion temperature sufficient to provide pressure against the bushing. The assembly under substantially non-oxidizing conditions is then subjected to solid state diffusion at an elevated solid state temperature corresponding to at least about 50% of the absolute melting point (solidus) of the metal part for a time at least sufficient to diffusion bond the bushing under pressure to the metal part by virtue of the expansion of the mandrel in the bushing at the diffusion temperature. The assembly is cooled to ambient, the mandrel removed, and the inner diameter of the diffusion-bonded bushing machined to an appropriate dimension. The diffusion-bonded part is preferably heat treated prior to machining of the bushing.

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First Claim