Effect of deformation temperature on precipitation, microstructural evolution, mechanical and corrosion behavior of 6082 Al alloy

The influence of cryorolling (CR), room temperature rolling (RTR) and post annealing on precipitation, microstructural evolution (recovery, recrystallisation and grain growth), mechanical and corrosion behavior, was investigated in the present work. The precipitation kinetics and microstructural morphology of CR, RTR, and post annealed samples were investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron back scattered diffraction (EBSD) to elucidate the observed mechanical properties. After annealing at 200 °C, UTS and hardness of CR samples (345 MPa and HV 127) were improved as compared to RTR samples (320 MPa and HV 115). The increase in hardness and UTS of CR samples after annealing at 200 °C was due to precipitation of β″ from Al matrix, which imparted higher Zener drag effect as compared to RTR samples. The improvement in corrosion and pitting potentials was observed for CR samples (−1.321 V and −700 mV) as compared to RTR samples (−1.335 V and −710 mV). In CR samples, heavy dislocation density and dissolution of Mg4Al3Si4-precipitates in the Al matrix have improved corrosion resistance of the alloy through formation of protective passive layer and suppression of galvanic cell, respectively.