Adequabilidade das condições de laminação de um aço baixo-carbono à estampagem profunda

Abstract

Some properties of polycrystalline materials depends on the direction in which they are measured. This is due to the occurrence of texture, i. e., a preferred orientation developed by the crystallites that is caused by, for example, a plastic deformation process or a heat treatment. Texture influences materials properties in a beneficial as well as a deleterious way. In the case of drawing soft drink cans, the beneficial influence of texture is the increase in strength in the normal direction of the sheet. However, texture can also cause earing and thinning of the wall adjacent to the cup bottom. The aim of this work is to study the relation between crystallographic texture, anisotropy and the degree of deep drawability for a low carbon steel used for the fabrication of gas containers. Samples of this steel were rolled in the range of temperatures between 600 ºC and 900 ºC. The results were compared to the ones obtained for an extra-low carbon steel grade used to make deep drawn soft drink cans. Texture was determined using orientation distribution functions calculated from 3 x-ray pole figures. The coefficients normal anisotropy (rm) and planar anisotropy (Dr) were determined from the Lankford coefficients for the rolling direction, transversal direction and the direction 45º between them. The deep drawability degree was measured by the modified Erichsen test for deep drawability. This test relates the deep drawability degree to the sheet thickness. Texture analyse results of rolled steels in temperatures between 600ºC and 900ºC are similar to a deep drawing steel for making cans for storage of soft drinks. Normal anisotropy (rm) and planar (Dr) coefficients have satisfactory values in agreement with the requirement for the same application. The deep drawability degree of most of the samples of rolled steel sheets in temperatures between 600ºC and 900ºC are appropriate for the production of soft drink cans.