Prediction of Lankford Coefficients for AA1050 and AA5754 Aluminum Sheets Using Uniaxial Tensile Tests and Cup Drawing Experiments

Abstract

Rolled sheet metals show different mechanical properties and stretching ability in different directions. Anisotropy of these metals should be defined in order to model the behavior of material in different directions for forming operations. Plastic anisotropy of sheet metals is characterized by Lankford Coefficients (R-values). Uniaxial tensile tests are usually employed to determine Lankford coefficients. However, some metals, like aluminum, have limited elongations under uniaxial tension, and the accuracy of tensile tests may be adversely affected due to low elongation before fracture. Recently, instead of uniaxial tensile tests, cup drawing approach is preferred to determine anisotropic properties of sheet metals with low uniaxial elongations. In this study, uniaxial tensile tests were carried out to obtain Lankford Coefficients of AA1050 and AA5754 aluminum sheets in the rolling direction (RD), diagonal direction (DD) at an angle of 45° to rolling, and perpendicular (transverse) direction (TD) to rolling. Subsequently, cup drawing experiments were conducted to predict Lankford coefficients using an analytical approach based on relevant literature. The results obtained from uniaxial tensile tests were compared with those obtained from cup drawings.