Texture Control of Aluminum, Iron, and Magnesium Alloy Sheets to Increase Their Plastic Strain Ratios

摘要

It is known that the limiting drawing ratio of sheet metals is proportional to their plastic strain ratios, and the plastic strain ratios of fcc and bcc metal sheets increase with increasing <111>//ND component in their textures. Conventional cold rolling and subsequent annealing of fcc metals cannot give rise to the <111>//ND component. Specifically, the cold rolling texture of polycrystalline fcc metals is characterized by the fiber connecting the {112}<111>, {123}<634>, and{011}<211> orientations in the Euler space, which is often called the β-fiber. The density of each component in the fiber depends on the stacking fault energy of metals. The {112}<111> and {123}<634> textured Al alloy sheets evolve the {001}<100> texture, when recrystallized. The low plastic strain ratios of the Al alloy sheets are attributed to the {001}<100> texture. The <111>//ND texture can be obtained in shear deformed fcc sheets. Bcc steels develop the <111>//ND texture when cold rolled and recrystallized. However, the density of <111>//ND depends on the content of dissolved interstitial elements such as carbon and nitrogen. The density of the <111>//ND component decreases with increasing concentration of the dissolved interstitial elements. For a given steel, the density of the <111>//ND component can vary with varying thermomechanical treatment. Magnesium alloy sheets are subjected to sheet forming processes at temperatures of 200°C or higher because of their basal plane texture, or the <0002>//ND orientation. Many studies have been made to alleviate the component so that the magnesium alloy sheets can have better formability. In this article, the above issues are briefly reviewed and discussed.