For non-quenchable dual-phase(DP)steel sheet,the warm forming process can effectively reduce the amount of springback,and the mechanical parameters that influence its elastic and inelastic recovery to decrease exhibit...For non-quenchable dual-phase(DP)steel sheet,the warm forming process can effectively reduce the amount of springback,and the mechanical parameters that influence its elastic and inelastic recovery to decrease exhibit a strong temperature dependence,especially under cyclic loading conditions.In this paper,the monotonic and cyclic loading tests of DP980 steel sheets are conducted at the temperatures ranging from 25℃ to 500℃.The temperature-dependent flow stress,nonlinear elastic recovery,and Bauschinger effect are investigated.The results demonstrate that both the elastic modulus and Bauschinger effect show an exponential law with pre-strain,and decrease with the increase of forming temperature,while there will be an abnormal phenomenon of rebound due to the influence of dynamic strain aging effect.Meanwhile,a linear relationship between the Bauschinger effect and inelastic strain is observed at various temperatures,and the weight of the Bauschinger effect in the total strain reduces with temperature increasing,which indicates that the springback is dominated by linear elastic recovery.Furthermore,the U-draw bending tests are carried out to clarify the influence of Vickers hardness distribution and martensite size effect on the springback behavior.展开更多
We studied precipitation patterns in a Liesegang system under microwave irradiation in order to investigate metal salt diffusion in an electrolyte gel. The salt species and microwave irradiation power were varied. Mic...We studied precipitation patterns in a Liesegang system under microwave irradiation in order to investigate metal salt diffusion in an electrolyte gel. The salt species and microwave irradiation power were varied. Microwave irradiation induced periodic patterns of precipitation because polar molecules vibrate and rotate in an electromagnetic field. For example, the number of patterns increased with the irradiation power. Accordingly, microwave irradiation nonlinearly accelerated the diffusion of ionic molecules.展开更多
Effective thermal conductivity with convection and radiation is analyzed by the homogenization method. This method can precisely represent the microstructure of a packed bed. In this study, the effects of parameters s...Effective thermal conductivity with convection and radiation is analyzed by the homogenization method. This method can precisely represent the microstructure of a packed bed. In this study, the effects of parameters such as the radiation emissivity, temperature, contact area and particle size of the packed bed on the conductivity have been estimated. For example, heat transfer by radiation does not dominate if the material has voids of less than l mm in size. Moreover, the effects of contact area and pressure on effective thermal conductivity are negligible for thermal radiation. By considering the microscopic behavior of a packed bed, the homogenization method is thus a powerful tool for estimating the bed＇s effective thermal conductivity.展开更多
基金Projects(2020JJ4578, 2019JJ50604) supported by the Natural Science Foundation of Hunan Province,ChinaProject(19A499) supported by the Key Program of the Scientific Research Foundation of the Education Department of Hunan Province,China。
文摘For non-quenchable dual-phase(DP)steel sheet,the warm forming process can effectively reduce the amount of springback,and the mechanical parameters that influence its elastic and inelastic recovery to decrease exhibit a strong temperature dependence,especially under cyclic loading conditions.In this paper,the monotonic and cyclic loading tests of DP980 steel sheets are conducted at the temperatures ranging from 25℃ to 500℃.The temperature-dependent flow stress,nonlinear elastic recovery,and Bauschinger effect are investigated.The results demonstrate that both the elastic modulus and Bauschinger effect show an exponential law with pre-strain,and decrease with the increase of forming temperature,while there will be an abnormal phenomenon of rebound due to the influence of dynamic strain aging effect.Meanwhile,a linear relationship between the Bauschinger effect and inelastic strain is observed at various temperatures,and the weight of the Bauschinger effect in the total strain reduces with temperature increasing,which indicates that the springback is dominated by linear elastic recovery.Furthermore,the U-draw bending tests are carried out to clarify the influence of Vickers hardness distribution and martensite size effect on the springback behavior.
文摘We studied precipitation patterns in a Liesegang system under microwave irradiation in order to investigate metal salt diffusion in an electrolyte gel. The salt species and microwave irradiation power were varied. Microwave irradiation induced periodic patterns of precipitation because polar molecules vibrate and rotate in an electromagnetic field. For example, the number of patterns increased with the irradiation power. Accordingly, microwave irradiation nonlinearly accelerated the diffusion of ionic molecules.
文摘Effective thermal conductivity with convection and radiation is analyzed by the homogenization method. This method can precisely represent the microstructure of a packed bed. In this study, the effects of parameters such as the radiation emissivity, temperature, contact area and particle size of the packed bed on the conductivity have been estimated. For example, heat transfer by radiation does not dominate if the material has voids of less than l mm in size. Moreover, the effects of contact area and pressure on effective thermal conductivity are negligible for thermal radiation. By considering the microscopic behavior of a packed bed, the homogenization method is thus a powerful tool for estimating the bed＇s effective thermal conductivity.
