The effect of extrusion on grain refinement has been studied in the AZ91 cast ingots. It is found that grain sizesmaller than 10μm can be obtained by the extrusion processing. Vickers hardness measurements were also ...The effect of extrusion on grain refinement has been studied in the AZ91 cast ingots. It is found that grain sizesmaller than 10μm can be obtained by the extrusion processing. Vickers hardness measurements were also carriedout to evaluate the effect of these processes on the room temperature mechanical properties. The experimentalresults of high temperature tensile tests revealed that the stress was inversely proportional to the square of the grainsize and that the activation energy for superplastic flow was higher than that for grain boundary diffusion.展开更多
Two-dimensional rigid-plastic finite element method (FEM) was used for simulation of the effect of process parameterson the static recrystallization of 60SiMnA spring steel using MARC/AutoForge 3.1 software. A thermo-...Two-dimensional rigid-plastic finite element method (FEM) was used for simulation of the effect of process parameterson the static recrystallization of 60SiMnA spring steel using MARC/AutoForge 3.1 software. A thermo-mechanicalcoupled analysis was conducted considering the heat transfer between the workpiece, the roll and the environment,and the heat generation due to plastic work. The static recrystallization laws under different processing conditionsand the predicted distribution of the static recrystallization volume fraction on the deformation cross section arepresented.展开更多
The Effect of the thermal cycling training under constant strain on the two-way shape memory effect (TWSME) in a Ti36l\li49Hf15 high temperature shape memory alloy (SMA) has been investigated by bending tests. The res...The Effect of the thermal cycling training under constant strain on the two-way shape memory effect (TWSME) in a Ti36l\li49Hf15 high temperature shape memory alloy (SMA) has been investigated by bending tests. The results indicated that the training procedure is beneficial to get the better TWSME. The two-way shape memory strain increases with increasing the training strain. And it decreases with increasing the training temperature. The TWSME obtained in the present alloy shows poorer stability compared with that obtained in the TiNi alloys.展开更多
Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been ...Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is stili unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the vvorking angle, the axial feeding rate, and the acceptable vvorking course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the bail diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.展开更多
Zn nanodot array was prepared by using a nano-masking with porous alumina membrane as mask. Based on such a nanodot array, a self-catalysis method was developed for fabricating ZnO nanopillars on Si substrate. The res...Zn nanodot array was prepared by using a nano-masking with porous alumina membrane as mask. Based on such a nanodot array, a self-catalysis method was developed for fabricating ZnO nanopillars on Si substrate. The resultant nanopillars show a two-dimensional, and regular array with uniform size and orientation.展开更多
基金The autlors gratefully acknowledge the financial support from the National Commnittee for High Technology ResearchDevelopment of China under the project No.2002AA331120.
文摘The effect of extrusion on grain refinement has been studied in the AZ91 cast ingots. It is found that grain sizesmaller than 10μm can be obtained by the extrusion processing. Vickers hardness measurements were also carriedout to evaluate the effect of these processes on the room temperature mechanical properties. The experimentalresults of high temperature tensile tests revealed that the stress was inversely proportional to the square of the grainsize and that the activation energy for superplastic flow was higher than that for grain boundary diffusion.
文摘Two-dimensional rigid-plastic finite element method (FEM) was used for simulation of the effect of process parameterson the static recrystallization of 60SiMnA spring steel using MARC/AutoForge 3.1 software. A thermo-mechanicalcoupled analysis was conducted considering the heat transfer between the workpiece, the roll and the environment,and the heat generation due to plastic work. The static recrystallization laws under different processing conditionsand the predicted distribution of the static recrystallization volume fraction on the deformation cross section arepresented.
文摘The Effect of the thermal cycling training under constant strain on the two-way shape memory effect (TWSME) in a Ti36l\li49Hf15 high temperature shape memory alloy (SMA) has been investigated by bending tests. The results indicated that the training procedure is beneficial to get the better TWSME. The two-way shape memory strain increases with increasing the training strain. And it decreases with increasing the training temperature. The TWSME obtained in the present alloy shows poorer stability compared with that obtained in the TiNi alloys.
文摘Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is stili unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the vvorking angle, the axial feeding rate, and the acceptable vvorking course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the bail diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50172030)the Tianjin Natural Science Foundation(Grant No.023617311).
文摘Zn nanodot array was prepared by using a nano-masking with porous alumina membrane as mask. Based on such a nanodot array, a self-catalysis method was developed for fabricating ZnO nanopillars on Si substrate. The resultant nanopillars show a two-dimensional, and regular array with uniform size and orientation.
