Phono-fission reactions and neutron emissions are triggered by high-frequency pressure waves in inert, non-radioactive materials. This phenomenon has previously been treated for brittle rocks. In the present chapter, the investigation is extended to a more ductile material, like steel, subjected to different loading conditions. Although phono-fission reactions are more likely to take place during the failure of brittle materials, the phenomenon is revealed also with the more ductile failure of metallic materials.