Asymmetric rolling of interstitial free steel sheets: Microstructural evolution and mechanical properties

Abstract

Asymmetric rolling (ASR) is a promising method for introducing shear deformation throughout the thickness of sheets. The induced shear deformation in ASR will result in texture evolution and which could also affect microstructural features controlling mechanical properties (such as the tensile strength). The main objective of this work consists of the investigation of the influence of ASR process on microstructure and texture evolution and their induced mechanical properties in interstitial free (IF) steel sheets. Both reverse and continuous asymmetric rolling were carried out to deform IF steel sheets. The results of optical microscopy observations showed no significant differences between the grain morphology of asymmetric and conventionally rolled (CR) samples. However, the obtained results of transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) indicated that fine and equiaxed microstructure was formed through the asymmetric rolling process. Texture evolution through plastic deformation has also been analyzed using X-ray diffraction. In addition, polycrystalline plasticity simulations were used to predict the texture evolution and the induced mechanical properties. The effect of the induced amount of pre-straining on the mechanical response of the samples through uniaxial tensile test has been studied. Results showed that at low thickness reductions (18%) the asymmetric rolled sample presents higher stress than that of the conventionally rolled sheet; while for higher thickness reductions (60%) the trend is reversed.