Due to the great effect of defects on the properties of materials including strength, ductility, resistivity and opacity, many techniques are used in defect detecting. In this work, positron annihilation lifetime technique (PALT), positron annihilation doppler Broadening technique (PADBT), and Vickers hardness (HV) were used to study the influence of plastic deformation on the properties of 3004 Al-alloy. The mean crystallite size measured by Positron annihilation lifetime technique, doppler Broadening technique and Vickers hardness test (HV) decrease as thickness reduction increases. A good correlation between the three techniques (PALT, PADBT and HV) for mean crystallite size was found. The dislocation density values at different degrees of deformation by VHT are larger compared to DBT and PALT.