Development of rolling textures in aluminum alloy 3004 subjected to varying hot-rolling deformation
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I.
INTRODUCTION
IT has been established that dilute aluminum alloys develop a texture of the "copper" or "pure metal" type when rolled. [1] This is primarily due to the high-stacking fault energy of the metal, which ensures that deformation proceeds by slip processes and mechanical twinning does not occur. The development of texture is commercially significant, as it is principally the type and strength of texture which determine the anisotropy of plastic flow in the material during forming operations. An important example of this plastic anisotropy occurs when cups are drawn deep from circular blanks cut from textured sheet. If the plastic flow properties vary with angle around the sheet, the flow of metal will be uneven, and this gives rise to an undulating rim with a number of high points, commonly called ears, and an equal number of low points, called troughs. [2J This manifestation of sheet or planar anisotropy is known as earing. It is well known that rolling textures of the pure metal type impart the tendency for ears to be formed at all positions in the cup, which are oriented approximately 45 deg to the rolling direction (in fact, closer to 48 deg). The literature has been dominated by results obtained from cold-rolled material, and little attention has been given to the effects of temperature on rolling texture development. A notable exception is the well-documented study by Dillamore and Roberts Ill of the texture transitions between the pure metal and alloy type which occur in copper and a brass with changing temperature. Aluminum alloy AA 3004 is extensively used in the production of the seamless body in two-piece all-aluminum cans by cupping from sheet, followed by drawing and ironing. A typical fabrication route for the sheet involves direct-chill semicontinuous casting, hot rolling, annealing, and cold rolling to the final gage. In the work reported here, AA 3004 has been rolled to various reductions and various temperatures in the range of 20 ~ to 520 ~ in multipass schedules. The textures at the midplanes of the rolled pieces were determined, and the results reported.
P.A. HOLLINSHEAD, formerly with the Department of Materials, Imperial College, London, is with the ALCOA Technical Center, Pittsburgh, PA 15069. T. SHEPPARD, Professor of Industrial Metallurgy, is with the Imperial College of Science and Technology, London S.W.7, United Kingdom. Manuscript submitted June 1, 1988. METALLURGICAL TRANSACTIONS A
II.
EXPERIMENTAL METHODS
Aluminum alloy AA 3004, having the chemical composition given in Table I, was direct-chill semicontinuously cast by ALCOA. The ingot was sectioned into slabs 300 mm long, 65 mm wide, and 48 mm thick. These were homogenized at 600 ~ in an air-circulating furnace. Heating and reheating for rolling were also carried out in this furnace, a small thermal head (6 ~ at 520 ~ 2 ~ to 3 ~ at 220 ~ being supplied to compensate for temperature loss during transfer from furnace to rolls. Reductions of 27, 48, 63, 71, 77, and 83 pct were applied at 20 ~ 220 ~ 400 ~ and 520 ~ in a
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