Development of ferrite rolling textures in low- and extra low-carbon steels
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I.
INTRODUCTION
THE development of rolling textures
in steels has been studied by numerous investigators, tl-~l] In microalloyed grades, such texture development begins during finish rolling in the austenite domain, because static recrystallization is suppressed in this temperature range. The deformation textures formed in this way are retained until the beginning of the 3'-to-a transformation. Although the reorientations taking place during transformation reduce the severity of the austenite textures, orientation distribution function (ODF) peaks nevertheless remain, which are then modified and intensified by further rolling in the ferrite phase, t~~ By contrast, in plain carbon steels, austenite textures are much less marked as a result of the randomizing effect of the recrystaUization that takes place between finishing passes, t1~ In both types of material, the final texture present after either warm or cold rolling depends on how individual grains are reoriented during deformation of the a phase. Several experimental and theoretical studies have been carded out to characterize the observed changes. The former include the rolling of samples with strong ideal components t~'4] and the measurement of intensity variations along the fibers as a function of strain.J6.91 The latter have involved simulations based on the Sachs, 121 Taylor, t2'5'sl and relaxed constraint [5,7,sl models of crystal plasticity. However, because of the complexities associated with grain rotations caused by a combination of austenite rolling, phase transformation, and ferrite rolling, the full effect of the latter is not yet completely clear. The present work was undertaken in order to clarify some of the contradictions present in experimental data regarding the orientation changes produced by cold rolling. For this purpose, the rate-dependent model of crystallographic glide wos employed, and mixed {112} (111) and {110} (111) slip was assumed to take place. L.S. TOTH, Associate Professor, is with the Institute for General Physics, EBtvfs University, 1445 Budapest, Hungary. J.J. JONAS, CSIRA/NSERC Professor of Steel Processing, and D. DANIEL, Research Associate, are with the Department of Metallurgical Engineering, McGill University, Montreal, PQ H3A 2A7, Canada. R.K. RAY, Professor, is with the Department of Metallurgical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016, India. Manuscript submitted January 2, 1990. METALLURGICALTRANSACTIONSA
For simulation purposes, various initial textures were studied, which were represented by Gaussian distributions about selected ideal components. The reorientation of these components was then followed as a function of strain using the full constraint (Taylor) and two relaxed constraint (lath and pancake) grain interaction models. It was found that the experimental observations can only be reproduced by employing all three deformation modes. The preferred deformation mode for a given grain is the one that requires the least work (lowest Taylor factor) and therefore depends on orienta
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