Orientation Preference of Recrystallization in Supersaturated Aluminum Alloys Influenced by Concurrent Precipitation
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THE control of grain size and texture is of important concern in aluminum sheet production, and recrystallization plays a vital part in the thermo-mechanical processing. Commercial aluminum usually contains second-phase particles formed during casting, and a large amount of alloying elements and impurities remain in solid solution, leading to precipitation during subsequent heat treatments. In supersaturated alloys, precipitation might occur during back annealing, which can interact with and strongly affect the recrystallization behavior. The recrystallization behavior of supersaturated alloys is divided into three regimes[1]: (I) precipitation prior to recrystallization; (II) precipitation and recrystallization occur concurrently; and III) recrystallization before precipitation. In regime I & II, a high density of fine precipitates induces a strong Zener drag effect, leading to slow recrystallization kinetics and coarse elongated grains.[2–7] By contrast, coarse particles can accelerate recrystallization by particle-stimulated QINGLONG ZHAO, formerly Researcher with the Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway, is now Associate Professor with the Key Laboratory of Automobile Materials, Ministry of Education, and Department of Materials Science and Engineering, Jilin University, Changchun 130025, P.R. China. Contact e-mails: qinglong. [email protected], [email protected] KE HUANG, Scientist, is with Laboratory of Thermomechanical Metallurgy - PX Group Chair, Ecole Polytechnique Fe´de´rale de Lausanne, Neucha˜tel CH-2002, Switzerland. YANJUN LI and KNUT MARTHINSEN, Professors, are with Department of Materials Science and Engineering, Norwegian University of Science and Technology. Contact e-mail: knut.marthinsen@ ntnu.no Manuscript submitted June 13, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS A
nucleation (PSN), for which recrystallization originates at subgrains in the deformation zones which develop around coarse particles at large strains.[8] Three-dimensional (3D) characterization in a particle-containing AA3104 alloy cold rolled to a reduction of 80 pct in thickness has shown that most of the nuclei are formed around clusters/bands of coarse particles.[9] The development of PSN in polycrystalline materials usually weakens the texture.[10,11] Nevertheless, in alloys containing coarse particles, it is often found in conditions of strong concurrent precipitation, strong P (typically {011} h566i) and ND-rotated cube ({001} h310i) texture components may develop during recrystallization.[3,5–7] Numerical simulations and electron back scattering diffraction (EBSD) observations have demonstrated that P orientations tend to form ahead of the coarse particle and that ND-rotated cube grains also originate within deformation zones.[12,13] It is suggested that these texture components are favored due to their low stored energy, which is indicated by Taylor factor.[14,15] It is further reported that the P-texture becomes more pronounced fo
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