Evolutions of the microstructure, texture and mechanical properties of a cold rolled Al-0.8Mg-0.8Si-0.66Cu-0.1Fe-0.12Cr alloy

Abstract

The evolutions of microstructure, texture and mechanical properties of an Al–Mg–Si–Cu alloy subject to cold rolling were investigated by scanning electron microscope, transmission electron microscope, electron backscattering diffraction and x-ray diffraction in this study. The evolution of the shape of grains was characterized by EBSD. TEM was used to observe the distribution of the dislocations. The texture of the rolled alloy was analyzed using x-ray diffraction. In addition, the fracture morphologies of the samples after tensile deformation were observed by SEM. The results revealed that the grain size decreases during the cold rolling process, accompanied by increase of the dislocation density. High density of the dislocations and dislocation tangles resulted in the formation of subgrains. In addition, when the thickness reduction is large enough, about 70%, β fiber formed run though the Euler angle space from the Copper orientation {1 1 2}〈1 1 1〉 through the S orientation {1 2 3}〈6 3 4〉 to the Brass orientation {0 1 1}〈2 1 1〉 according to the x-ray diffraction results. The intensity of β-fiber increases with the increase of the thickness reduction. With the thickness reduction increases to 90%, the intensity of β fiber increases to the highest value. The cold rolled Al–Mg–Si–Cu alloy with a rolling reduction of 90% has excellent comprehensive mechanical properties along 45° to the rolling direction, with the yield strength and tensile strength being about 265 MPa and 280 MPa, respectively, and the elongation being about 12.6%. The yield strength and elongation have improvements of about 12% and 52% compared to the sample stretched along the rolling direction.