Size effect on indentation depth of oxygen-free high purity copper induced by laser shock processing

The research was carried out on the sheet metal samples of oxygen-free high purity copper to investigate the size effect on the indentation depth induced by laser shock. Samples were annealed at different temperatures and holding time to obtain microstructures with different grain sizes at the cross-section of thickness. Two spot sizes were used for experiments to obtain different loading sizes with different numbers of grains covered. The depth of indentation was measured to analyze size effects on the deformation at high strain rates. The results show that although the same pulse energy is adopted, the laser shock with the larger laser spot induces deep indentation more easily. The grain size has a notable effect on the indentation depth. It is difficult to generate plastic deformation in material with fine grains. The interactive effect of the thickness, laser spot, and grain sizes are found not to be important for the indentation depth when samples with coarse grains are used for experiments.