Advanced high-strength steels have been widely used to improve the crashworthiness and lightweight of vehicles.Different from the popular cold stamping,hot forming of boron-alloyed manganese steels,such as 22MnB5,coul...Advanced high-strength steels have been widely used to improve the crashworthiness and lightweight of vehicles.Different from the popular cold stamping,hot forming of boron-alloyed manganese steels,such as 22MnB5,could produce ultra-high-strength steel parts without springback and with accurate control of dimensions.Moreover,hot-formed medium-Mn steels could have many advantages,including better mechanical properties and lower production cost,over hot-formed 22MnB5.This paper reviews the hot forming process in the automotive industry,hot-formed steel grades,and medium-Mn steel grades and their application in hot forming in depth.In particular,the adaptabilities of medium-Mn steels and the presently popular 22MnB5 into hot forming were compared thoroughly.Future research should focus on the technological issues encountered in hot forming of medium-Mn steels to promote their commercialization.展开更多
A simultaneous prediction of macroscopic deformation and microstructure evolution is critical for un-derstanding the deformation mechanism of components.In this work,the hydro-bulging process of 2219 aluminum alloy sh...A simultaneous prediction of macroscopic deformation and microstructure evolution is critical for un-derstanding the deformation mechanism of components.In this work,the hydro-bulging process of 2219 aluminum alloy sheet was investigated using cross-scale numerical modeling,in which the macroscopic finite element method(FEM)and crystal plasticity finite element method(CPFEM)were combined.The calculated texture evolution exhibits good agreement with the experimental results,and the stress er-ror between the two scales is generally small.The effects of different strain states on texture evolution and slip mode are further discussed.As the strain ratioηincreases,the volume fractions of the initial Rotated Copper texture component andγ-Fiber texture component decrease significantly,which tend to be stabilized at P texture component.The initial Rotated Cube texture component is inclined to rotate towards the Cube texture component,while the volume fraction of this orientation is relatively stable.The lower strain ratio can considerably enhance the activity of more equivalent slip systems,promoting a more uniform strain distribution over grains.The difficulty of grain deformation changes as the lat-tice rotates.The grain with easy-to-deform orientation can gradually rotate to a stable orientation during plastic deformation,which has a lower Schmid factor.展开更多
Single mature Retzius cells which contain 5-HT have been implanted in isolated ganglia of Whitmania pigra. The properties of the implanted Retzius cell and its connections with the original identified nerve cells of t...Single mature Retzius cells which contain 5-HT have been implanted in isolated ganglia of Whitmania pigra. The properties of the implanted Retzius cell and its connections with the original identified nerve cells of the ganglia have been measured by intracellular microelectrodes. At 3 days in culture an implanted Retzius cell maintains its normal electrical membrane properties. It also forms the non-rectifying electronic coupling with the original Retzius cell and rectifying junctions with the L motor neuron of the host ganglion. In addition it receives chemical inputs of the impulse from T and N sensory neurons of ganglion. Impulses in the implanted Retzius cell evoke synaptic potentials in the L motor neuron, In this paper the appearance of novel synapses, which are formed by implanting an extra mature neuron as a pre- or post-synaptic element, is described. It might represent functional development of central nervous system at an earlier stage.展开更多
The metal goes into the plastic deformation after the application of external load. Most of the metal forming industries work on this principle of plastic deformation. Thus the understanding of plastic deformation in ...The metal goes into the plastic deformation after the application of external load. Most of the metal forming industries work on this principle of plastic deformation. Thus the understanding of plastic deformation in the metal forming industry is important. The research on the single material plastic deformation has been carried out from many centuries before the era of Tresca. In this study the two metals 0.05% C steel annealed (soft metal) and 0.6% C steel quenched and tempered (hard metal) were deformed plastically in the parallel combination in the composite form. This study has been carried out with simple mathematical theory and simulated numerical model. The comparison shows the exact match between the mathematical and numerical results. It is also observed that the individual metal thickness affects the deformation flow curve.展开更多
基金The authors acknowledge the financial supports from the National Natural Science Foundation of China(Nos.51861135302 and 51831002)Fundamental Research Funds for the Central Universities,China(No.FRF-TP-18-002C2).
文摘Advanced high-strength steels have been widely used to improve the crashworthiness and lightweight of vehicles.Different from the popular cold stamping,hot forming of boron-alloyed manganese steels,such as 22MnB5,could produce ultra-high-strength steel parts without springback and with accurate control of dimensions.Moreover,hot-formed medium-Mn steels could have many advantages,including better mechanical properties and lower production cost,over hot-formed 22MnB5.This paper reviews the hot forming process in the automotive industry,hot-formed steel grades,and medium-Mn steel grades and their application in hot forming in depth.In particular,the adaptabilities of medium-Mn steels and the presently popular 22MnB5 into hot forming were compared thoroughly.Future research should focus on the technological issues encountered in hot forming of medium-Mn steels to promote their commercialization.
基金financially supported by the National Natural Science Foundation of China(No.52275322)the Heilongjiang Touyan Team(No.HITTY-20190015).
文摘A simultaneous prediction of macroscopic deformation and microstructure evolution is critical for un-derstanding the deformation mechanism of components.In this work,the hydro-bulging process of 2219 aluminum alloy sheet was investigated using cross-scale numerical modeling,in which the macroscopic finite element method(FEM)and crystal plasticity finite element method(CPFEM)were combined.The calculated texture evolution exhibits good agreement with the experimental results,and the stress er-ror between the two scales is generally small.The effects of different strain states on texture evolution and slip mode are further discussed.As the strain ratioηincreases,the volume fractions of the initial Rotated Copper texture component andγ-Fiber texture component decrease significantly,which tend to be stabilized at P texture component.The initial Rotated Cube texture component is inclined to rotate towards the Cube texture component,while the volume fraction of this orientation is relatively stable.The lower strain ratio can considerably enhance the activity of more equivalent slip systems,promoting a more uniform strain distribution over grains.The difficulty of grain deformation changes as the lat-tice rotates.The grain with easy-to-deform orientation can gradually rotate to a stable orientation during plastic deformation,which has a lower Schmid factor.
基金Project supported by the National Natural Science Foundation of China
文摘Single mature Retzius cells which contain 5-HT have been implanted in isolated ganglia of Whitmania pigra. The properties of the implanted Retzius cell and its connections with the original identified nerve cells of the ganglia have been measured by intracellular microelectrodes. At 3 days in culture an implanted Retzius cell maintains its normal electrical membrane properties. It also forms the non-rectifying electronic coupling with the original Retzius cell and rectifying junctions with the L motor neuron of the host ganglion. In addition it receives chemical inputs of the impulse from T and N sensory neurons of ganglion. Impulses in the implanted Retzius cell evoke synaptic potentials in the L motor neuron, In this paper the appearance of novel synapses, which are formed by implanting an extra mature neuron as a pre- or post-synaptic element, is described. It might represent functional development of central nervous system at an earlier stage.
文摘The metal goes into the plastic deformation after the application of external load. Most of the metal forming industries work on this principle of plastic deformation. Thus the understanding of plastic deformation in the metal forming industry is important. The research on the single material plastic deformation has been carried out from many centuries before the era of Tresca. In this study the two metals 0.05% C steel annealed (soft metal) and 0.6% C steel quenched and tempered (hard metal) were deformed plastically in the parallel combination in the composite form. This study has been carried out with simple mathematical theory and simulated numerical model. The comparison shows the exact match between the mathematical and numerical results. It is also observed that the individual metal thickness affects the deformation flow curve.
