Hot Deformation Behavior of a Differential Pressure Casting Mg-8Gd-4Y-Nd-Zr Alloy
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Hot Deformation Behavior of a Differential Pressure Casting Mg-8Gd-4Y-Nd-Zr Alloy Changping Tang, Wenhui Liu, Yuqiang Chen, Xiao Liu, and Yunlai Deng (Submitted November 28, 2015; in revised form October 14, 2016; published online November 17, 2016) To fabricate components with high performance, the compression behavior and microstructure evolution of a differential pressure casting Mg-8Gd-4Y-Nd-Zr alloy were investigated. The cylindrical samples were compressed at temperatures ranging from 350 °C to 525 °C and strain rates ranging from 0.001 s21 to 2 s21. For the compression at 350 °C, dynamic precipitation occurs and consumes much of the solutes in the matrix, which should be avoided. The recrystallized grain size (d) decreases when the proposed deformation parameter (Z) increases, and the resulting Z-d relationship is established. Finally, a superior deformation process of 500 °C/0.01 s21 is determined based on the experimental results. Moreover, a plate with an ultimate tensile strength of 413 MPa was fabricated. Keywords
dynamic precipitation, magnesium alloy, processing map, mechanical property, recrystallization
1. Introduction Magnesium alloys have great potential in the automotive and aerospace industries as they meet the combined demands of low density, good machinability and excellent damping capacity (Ref 1-3). Nevertheless, magnesium alloys exhibit low ductility below 225 C due to the limited number of slip systems associated with the intrinsic characteristics of the hexagonal-closed-packed (HCP) crystal structure (Ref 2). As a result, most of the magnesium products to date have been fabricated using casting. However, wrought magnesium alloys can have superior mechanical properties compared to the casting alloys. Fortunately, above 225 C, the workability of magnesium alloys will be enhanced greatly due to the activation of non-basal slip systems, such as prismatic slip systems and pyramidal slip systems, which makes the fabrication of complicated components possible. Moreover, dynamic recrystallization (DRX) is expected to occur during the deformation of magnesium alloys at elevated temperatures because of the low stacking fault energy, which may result in Changping Tang, School of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, PeopleÕs Republic of China; High Temperature Wear Resistant Materials and Preparation Technology of Hunan Province National Defence Science and Technology Laboratory, Xiangtan 411201, PeopleÕs Republic of China; and School of Materials Science and Engineering, Central South University, Changsha 410083, PeopleÕs Republic of China; Wenhui Liu, Yuqiang Chen, and Xiao Liu, School of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, PeopleÕs Republic of China; High Temperature Wear Resistant Materials and Preparation Technology of Hunan Province National Defence Science and Technology Laboratory, Xiangtan 411201, PeopleÕs Republic of China; and
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