Estimation of Planar and Normal Anisotropy Parameters of Al 8011 Sheets as Cold Rolled and Cold Rolled with Annealed Condition

Abstract

Aluminium 8011 cast plates subjected to cold rolling to reduce thickness from 12 mm to 3.5 sheets. As rolled aluminium sheet was subjected to annealing treatment after rolling. This work deals with the study of planar and normal anisotropy parameters of as rolled aluminium and rolled with annealed aluminium sheets. The tensile test samples were cut at 0°, 30°, 45°, 60° and 90° with respect to the rolling direction of as rolled Al sheet and rolled with annealed Al sheet. Tensile properties were measured at different orientations to the rolling directions. The wide variation in tensile strength was found in case of as rolled Al samples at different orientation to rolling direction of sheet (208 to 243 MPa). On the other hand nearly uniform tensile strength (128 MPa to 132 MPa) was measured for rolled and annealed Al samples at different orientations. As rolled Al samples shows anisotropic tensile properties where as isotropic tensile properties were measured for rolled with annealed Al samples. Al grains are more elongated along the rolling directions where as rolled and annealed Al sample shows more equiaxed grains which is attributed to isotropic behaviour of Al sheets. The normal anisotropy parameter or average rm value is higher (1.24) in case of rolled and annealed sheet sample as compared to as rolled Al sheet rm value (1.06). This is attributed to isotropic behaviour of rolled and annealed samples. Toughness and ductility properties are improved more than 3 times in case of rolled and annealed Al sheet samples. Annealing treatment of rolled Al sheet samples shows elongated grain morphology changes to equiaxed grains of aluminum which tends to improved formability and isotropic mechanical properties Al sheet. For determination of normal anisotropy (rm) value, tensile results R values are required at angles of 0 degrees, 45 degrees, and 90 degrees. However in this study additional R values are estimated at 30 degree and 60 degree in order to understand trend of R value at every 30 degree from 0 to 90 degree.