Pure Cu and an Al-3 %Mg-0.2 %Sc alloy are processed by high-pressure torsion with ring-shape samples having an initial thickness of 4 mm. Microstructural observation across the thickness is carried out using optical microscopy and transmission electron microscopy to correlate with hardness variation. It is shown that the strain is introduced more intensely in the center of thickness on the cross sections for both pure Cu and the Al alloy. This area expands with an increasing number of revolutions but the expansion saturates before covering the entire cross section. Softening occurs with straining in pure Cu but saturation reaches without softening in the Al alloy. It is suggested that imposed strain is estimated using the thickness of severely deformed region.