Microstructural evolution during reheating of A356 machining chips at semisolid state
来源期刊：International Journal of Minerals Metallurgy and Materials2017年第8期
论文作者：Fang Wang Wen-qiang Zhang Wen-long Xiao Hiroshi Yamagata Chao-li Ma
文章页码：891 - 900
摘 要：The microstructural evolution of A356 machining chips in the semisolid state was studied at different temperatures and holding times. The results showed that the elongated α-Al grains first recrystallized in the semisolid state and then became globular with a high shape factor（SF）. Both the temperature and the holding time clearly affected the grain size and SF. When the heating temperature or holding time was increased, the grain size and SF gradually increased and finally became stable. Moreover, the Vickers hardness of primary α-Al grains gradually decreased with increasing heating temperature. The optimal slurry for semisolid processing, with a good combination of grain size and SF, was obtained when the chips were held at 600℃ for 15 min. The semisolid slurry of A356 chips exhibited a lower coarsening rate of α-Al grains than those produced by most of the conventional semisolid processes. The coarsening coefficient was determined to be 436 μm3·s-1 on the basis of the linear Lifshitz–Slyozov–Wagner（LSW） relationship.
Fang Wang1，Wen-qiang Zhang1，Wen-long Xiao1，Hiroshi Yamagata2，Chao-li Ma1
1. Key Laboratory of Aerospace Advanced Materials and Performance of the Ministry of Education, School of Materials Science and Engineering, Beihang University2. Center for Advanced Die Engineering and Technology, Gifu University
摘 要：The microstructural evolution of A356 machining chips in the semisolid state was studied at different temperatures and holding times. The results showed that the elongated α-Al grains first recrystallized in the semisolid state and then became globular with a high shape factor（SF）. Both the temperature and the holding time clearly affected the grain size and SF. When the heating temperature or holding time was increased, the grain size and SF gradually increased and finally became stable. Moreover, the Vickers hardness of primary α-Al grains gradually decreased with increasing heating temperature. The optimal slurry for semisolid processing, with a good combination of grain size and SF, was obtained when the chips were held at 600℃ for 15 min. The semisolid slurry of A356 chips exhibited a lower coarsening rate of α-Al grains than those produced by most of the conventional semisolid processes. The coarsening coefficient was determined to be 436 μm3·s-1 on the basis of the linear Lifshitz–Slyozov–Wagner（LSW） relationship.
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