Analysis of distribution of deformations during tensile straightening of hot-rolled strips from aluminum alloys

Abstract

In order to reveal the regularities of the change in the dimensions of strips of aluminum alloys during their straightening by stretching, an industrial experiment was carried out on a straightening-stretching machine with a force of 70 MN. Certain control points were assigned on the plate surface and strip thicknesses were recorded there before and after straightening. The measurements were made on 12 hot-rolled plates with a thickness of 25–130 mm from four types of alloys. The sample size is divided into two parts: measuring points located at the periphery, closer to the grippers, and points in the central part of the workpiece. The coefficients of plastic anisotropy are determined. It was found that the coefficient of plastic anisotropy takes on higher values in the peripheral part of the strip than in the central one. For alloys D16, 5083 and AMg6, respectively, there is a general tendency: with increasing thickness, the coefficient of plastic anisotropy increases. In the course of statistical processing, along with the average values, the dispersions of the strip thicknesses before and after straightening were also determined. In the range of thicknesses 20–60 mm, we can talk about the approximate equality of dispersions. However, above 80 mm, the indicator begins to grow, while at a thickness of 130 mm, the dispersion increases by about four times relative to this characteristic for small thicknesses. In general, the setting of the strip elongation parameters during tension straightening should lead to such a change in thickness, which should provide the value in the tolerance field. It is shown that the change in strip thicknesses depends on the initial one obtained during rolling. At thicknesses of 100–130 mm, plastic deformation approaches the conditions of isotropic material`s deformation. For thinner hot-rolled strips, the coefficient of plastic anisotropy varies in the range of 0.4–0.9, and the greater the strip thickness, the greater it is.This work was carried out with partial financial support from Decree No. 211 of the Government of the Russian Federation, contract No. 02.A03.21.