Determination of in-plane anisotropy of rolled sheets, taking into account the effect of strain intensity

Abstract

The results of experimental studies of the mechanical properties anisotropy of rolled sheets made of NKh260YD steel are presented. Tension was applied to flat specimens cut in directions of 0, 45, and 90 degrees with respect to the rolling direction. A dividing grid was applied to the samples with a diamond indenter in the area of the estimated length on an instrumental microscope. Based on the results of measurements of the samples linear dimensions before and after deformation in the places where the dividing grid was applied, the logarithmic deformations were calculated over the width and thickness of the sample in each of the considered sections. The results of measurements and calculations showed the uneven intensity of deformations in its various sections. For further processing, data in sections under conditions of uniform deformation were used. The anisotropy coefficients were determined as the ratio of logarithmic strains over the width and thickness of the sample. The tension was carried out in three stages, which made it possible to establish the dependences of the anisotropy coefficients on the strain intensity, which were used to assess the degree of in-plane anisotropy of the material under study. Graphic dependences are presented illustrating the nature of the change in the anisotropy coeffi cients and the degree of anisotropy of the material under study depending on the intensity of deformation. A significant dependence of the HX260YD steel planar anisotropy degree on the magnitude of the strain intensity is shown, which must be taken into account when developing technological processes for production of critical articles from anisotropic sheet material by plastic shaping operations.