Investigation of Recrystallization Behaviors of CuZn30 Alloy After Flow Forming H. Kuşdemir∗, M. Mutlu Repkon Machine and Tool Industry, Istanbul 34980, Türkiye ∗ hakan.kusdemir@repkon.com.tr Keywords: Flow forming, Recrystallization Annealing, CuZn30 CuZn30 alloy is used widely in the manufacturing of large-caliber round cartridge cases. Generally they are manufactured by cupping of a disc and after that successive deep drawing processes in order to reduce the wall thickness of the material. Annealing process is applied between each process steps to recover formability [1]. The main target of this study is determining to optimum recrystallization annealing conditions of CuZn30 tubes after flow forming operation. Preforms which are used in the study is produced by machining of CuZn30 billets. They are one end closed with an outer diameter of 125.20 mm, wall thickness of 5.2 mm and 300 mm length. Flow forming process parameters are 110 mm/sec feed rate, 160 rpm rotation and 40% thickness reduction ratio. After flow forming, recrystallization annealing operations are applied at different temperatures which are 250◦C, 350◦C, 450◦C and 550◦C for 1 hour in atmosphere controlled furnace. Moreover, recrystallization annealing is also applied at similar temperatures in salt bath to decrease operation time. The obtained microstructures and the mechanical properties are investigated to determine optimum recrystallization annealing conditions. Spherical and new grains are obviously generated after recrystallization annealing at 450 and 550◦C, but only partial recrystallization is detected at 250 and 350◦C in atmosphere controlled furnace. Also, by using salt bath similar results are obtained in a very short times comparing to atmosphere controlled furnace. References [1] Doig, A. (1998). Military Metallurgy, pp. 23 - 29. 67
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