A method of processing a metal piece comprises a number of steps. One step comprises directing a laser beam onto the metal piece for laser peening the metal piece. Another step comprises causing relative movement between the laser beam and the metal piece. Another step comprises providing a tamping material between the laser beam and the metal piece. Another step comprises continuing the laser peening to induce rapid strain and substantial strain in the metal piece and inducing the formation of nanocrystalline structure in the metal piece.
 The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.