Industry pure zirconium sheets with a strong c-axis fiber texture were rolled to different strains at 77 K to investigate the twinning behavior and deformation mechanism. The microstructure and texture of the rolled s...Industry pure zirconium sheets with a strong c-axis fiber texture were rolled to different strains at 77 K to investigate the twinning behavior and deformation mechanism. The microstructure and texture of the rolled specimens were characterized by scanning electron microscopy （SEM） together with electron backscatter diffraction （EBSD） techniques. The results show that the {1022} （1123） compression twinning mode is the dominant deformation twin at low strains loaded along the c-axis, and the {1012} （ 10]- 1 ） tensile twinning generates as the second twin in {1022} （ 1123 ） twins. The selection of twinning modes is governed by Schmid factor （SF） due to the calculating of SF and the EBSD simulating of twinning distribution. The evolution of texture during rolling affected by twins with increase of the strain was explained.展开更多
Microstructure and texture evolution during high-strain-rate superplastic deformation of the rolled Mg-Gd-Y-Zr sheet were investigated.The tensile tests at the strain rate of 0.01 s-1 achieved the elongations of 180%-...Microstructure and texture evolution during high-strain-rate superplastic deformation of the rolled Mg-Gd-Y-Zr sheet were investigated.The tensile tests at the strain rate of 0.01 s-1 achieved the elongations of 180%-266% in the deformation temperature range of 400-500 ℃.Post-deforming microstructures were characterized by optical microscopy,scanning electron microscopy and transmission electron microscopy,while crystallographic orientation information was obtained from macro-texture analysis.The results show that the high strain-rate superplasticity was attributed to class-I dislocation creep accommodated by dynamic recrystallization （DRX）.During preheating at 435 ℃ for 600 s,twinning-induced recrystallization occurred.The initial strain of 80% made original grains fragmented and produced homogenous DRX grains.The interaction between dynamic recrystallization and dynamic precipitation yielded out such a phenomenon that finer DRX grains were often accompanied by denser particles.The macro-texture evolution exhibited some characteristics of the crystal rotation arising from basal slip and prismatic slip despite the occurrence of DRX.展开更多
To gain a better understanding about texture evolution during rolling process of AZ31 alloy, polycrystalline plasticity model was implemented into the explicit FE package, ABAQUS/Explicit by writing a user subroutine ...To gain a better understanding about texture evolution during rolling process of AZ31 alloy, polycrystalline plasticity model was implemented into the explicit FE package, ABAQUS/Explicit by writing a user subroutine VUMAT. For each individual grain in the polycrystalline aggregate, the rate dependent model was adopted to calculate the plastic shear strain increment in combination with the Voce hardening law to describe the hardening response, the lattice reorientation caused by slip and twinning were calculated separately due to their different mechanisms. The elasto-plastic self consistent （EPSC） model was employed to relate the response of individual grain to the response of the polycrystalline aggregate. Rolling processes of AZ31 sheet and as-cast AZ31 alloy were simulated respectively. The predicted texture distributions are in aualitative a^reement with experimental results.展开更多
The texture evolution and mechanical properties of Cu-Ag alloys subjected to severe plastic deformation at cryogenic temperature（CT） were investigated and the sequent annealing behaviors were also studied.Compared w...The texture evolution and mechanical properties of Cu-Ag alloys subjected to severe plastic deformation at cryogenic temperature（CT） were investigated and the sequent annealing behaviors were also studied.Compared with the sheets rolled at room temperature（RT） showing copper texture,the CT-rolled sheets exhibited brass texture which indicated that cross-slip was suppressed at CT,and both the ultimate tensile strength and yield strength of the sheets were increased.Due to the in-situ recrystallization mechanism,recrystallization textures in as-annealed CT-rolled sheets were randomly distributed,while the as-annealed RT-rolled sheets mainly contained cube texture.Microstructures of the rolled and annealed sheets were observed using optical microscopy and electronic back-scatter diffraction.The results show that the dynamic recovery was suppressed during CT-rolling and resulted in higher deformation energy storage.Therefore,the recrystallization of CT-rolled sheets could start at a lower temperature than that of RT-rolled sheet at the same reduction.展开更多
基金Project(51171213)supported by the National Natural Science Foundation of ChinaProject(NCET-08-0606)supported by New Century Excellent Talents in University,China
文摘Industry pure zirconium sheets with a strong c-axis fiber texture were rolled to different strains at 77 K to investigate the twinning behavior and deformation mechanism. The microstructure and texture of the rolled specimens were characterized by scanning electron microscopy （SEM） together with electron backscatter diffraction （EBSD） techniques. The results show that the {1022} （1123） compression twinning mode is the dominant deformation twin at low strains loaded along the c-axis, and the {1012} （ 10]- 1 ） tensile twinning generates as the second twin in {1022} （ 1123 ） twins. The selection of twinning modes is governed by Schmid factor （SF） due to the calculating of SF and the EBSD simulating of twinning distribution. The evolution of texture during rolling affected by twins with increase of the strain was explained.
基金Project supported by Natural Science Foundation of Hunan Province,China
文摘Microstructure and texture evolution during high-strain-rate superplastic deformation of the rolled Mg-Gd-Y-Zr sheet were investigated.The tensile tests at the strain rate of 0.01 s-1 achieved the elongations of 180%-266% in the deformation temperature range of 400-500 ℃.Post-deforming microstructures were characterized by optical microscopy,scanning electron microscopy and transmission electron microscopy,while crystallographic orientation information was obtained from macro-texture analysis.The results show that the high strain-rate superplasticity was attributed to class-I dislocation creep accommodated by dynamic recrystallization （DRX）.During preheating at 435 ℃ for 600 s,twinning-induced recrystallization occurred.The initial strain of 80% made original grains fragmented and produced homogenous DRX grains.The interaction between dynamic recrystallization and dynamic precipitation yielded out such a phenomenon that finer DRX grains were often accompanied by denser particles.The macro-texture evolution exhibited some characteristics of the crystal rotation arising from basal slip and prismatic slip despite the occurrence of DRX.
基金Projects(50821003,50405014)supported by the National Natural Science Foundation of ChinaProjects(10QH1401400,10520705000,10JC1407300)supported by Shanghai Committee of Science and Technology,China+1 种基金Project(NCET-07-0545)supported by Program for New Century Excellent Talents in University,ChinaFord University Research Program,China
文摘To gain a better understanding about texture evolution during rolling process of AZ31 alloy, polycrystalline plasticity model was implemented into the explicit FE package, ABAQUS/Explicit by writing a user subroutine VUMAT. For each individual grain in the polycrystalline aggregate, the rate dependent model was adopted to calculate the plastic shear strain increment in combination with the Voce hardening law to describe the hardening response, the lattice reorientation caused by slip and twinning were calculated separately due to their different mechanisms. The elasto-plastic self consistent （EPSC） model was employed to relate the response of individual grain to the response of the polycrystalline aggregate. Rolling processes of AZ31 sheet and as-cast AZ31 alloy were simulated respectively. The predicted texture distributions are in aualitative a^reement with experimental results.
基金Project(51271046)supported by the National Natural Science Foundation of China
文摘The texture evolution and mechanical properties of Cu-Ag alloys subjected to severe plastic deformation at cryogenic temperature（CT） were investigated and the sequent annealing behaviors were also studied.Compared with the sheets rolled at room temperature（RT） showing copper texture,the CT-rolled sheets exhibited brass texture which indicated that cross-slip was suppressed at CT,and both the ultimate tensile strength and yield strength of the sheets were increased.Due to the in-situ recrystallization mechanism,recrystallization textures in as-annealed CT-rolled sheets were randomly distributed,while the as-annealed RT-rolled sheets mainly contained cube texture.Microstructures of the rolled and annealed sheets were observed using optical microscopy and electronic back-scatter diffraction.The results show that the dynamic recovery was suppressed during CT-rolling and resulted in higher deformation energy storage.Therefore,the recrystallization of CT-rolled sheets could start at a lower temperature than that of RT-rolled sheet at the same reduction.
