Microstructural evolution of Al–Zn–Mg–Cu–(Sc) （Al-Zn-Mg-Cu显微组织演化的u2014u2014(Sc)）.pdfVIP

Journal of Materials Processing Technology xxx (2004) xxx–xxx Microstructural evolution of Al–Zn–Mg–Cu–(Sc) alloy during hot extrusion and heat treatments Dong-Woo Suh a,∗, Sang-Yong Lee a , Kyong-Hwan Leeb , Su-Keun Lim c , Kyu Hwan Oh d a Materials Processing Department, Korea Institute of Machinery and Materials, Changwon, Kyungnam 641-010, South Korea b Bowon Light Metal Co. Ltd., Hwaseong, Kyunggi 445-893, South Korea c Department of Metallurgical and Materials Engineering, Kyungsang National University, Chinju, Kyungnam 600-701, South Korea d School of Materials Science and Engineering, Seoul National University, Seoul 151-742, South Korea Abstract The microstructural evolution during hot extrusion and post heat treatment was investigated for two kind of Al–Zn–Mg–Cu–(Sc) alloy and AA7075. The microstructure of as-extruded bar is mainly comprised of recovered structure for all alloys, however, different restoration processes are observed during post heat treatment. For AA7075 and S1, which contains 0.1% Sc with relatively higher Zn and Cu content than S2, recovery still proceeds during the heat treatment, while the recrystallization becomes main restoration process during the heat treatment for S2. The differences in abnormal grain growth and hardening behavior between S1, AA7075 and S2 during the heat treatment are discussed in connection with the restoration processes and resultant microstructures. © 2004 Elsevier B.V. All rights reserved. Keywords: Scandium; Microstructure; Recovery; Recrystallization 1. Introduction has been carried out in this field and many aspects involved with hot working o