<p>The healing of cracks in metallic components fundamentally involves the exchange of material and energy within an open system. The processes involved include welding and laser repair various heat-treating techniques hot plastic deformation plasma spraying electro-healing electroplating gas carbonitriding friction stir welding electric current-pulsing thermo-mechanical coupling filling of cracks via oxide formation flash hot isostatic pressing and various ultrasonic methods. The book describes the various techniques their advantages and disadvantages.</p>