The phenomenon of stress-induced recrystallization (SIR) and recrystallization- induced plasticity (RIP) in DT4 pure iron was investigated by means of hightemperature tensile test under a constant elastic stress and ...The phenomenon of stress-induced recrystallization (SIR) and recrystallization- induced plasticity (RIP) in DT4 pure iron was investigated by means of hightemperature tensile test under a constant elastic stress and microstructural observation. It is shown that the macroscopic plastic flow of cold-rolled specimens, which occured during heating process under pre-loaded elastic stress, resulted from stressinduced recrystallization and recrystallization-induced plasticity. The characteristics and mechanism of this phenomenon were also preliminarily discussed.展开更多
An incremental updated Lagrangian elasto-plastic finite element method(FEM) was employed to analyze the hole-flanging with the ironing of circulate plates using a pre-determined smaller hole at the center of the two-p...An incremental updated Lagrangian elasto-plastic finite element method(FEM) was employed to analyze the hole-flanging with the ironing of circulate plates using a pre-determined smaller hole at the center of the two-ply sheet metals. An extended rmin technique was employed such that each incremental step size can be determined not only by the yielding of an element Gaussian point, but also by the change under the boundary conditions of penetration, separation, and the alternation of the sliding-sticking state of friction along the tool-sheet interface. Two-ply sheet metals are generally composed of metals that have different mechanical properties. Thus, the forming process of these materials is complicated. A number of experiments and simulations were performed using a conical punch with a cone angle of 45°. The experimental results were compared with FEM-simulated results. It is found that using the elasto-plastic FEM can effectively predict the generation process of the deformed shape until unloading. The calculated sheet geometries and the relationship between punch load and punch travel are in good agreement with the experimental data.展开更多
At room temperature,dry sliding wear tests were carried out using pin-on-disc test rig,in which the pin is made of vermicular iron and the disc is made of 40 Cr steel.The microstructures of the frictional surfaces for...At room temperature,dry sliding wear tests were carried out using pin-on-disc test rig,in which the pin is made of vermicular iron and the disc is made of 40 Cr steel.The microstructures of the frictional surfaces for the pin specimens were investigated.Under the action of both frictional heat and frictional shearing stress,aplastic deformation layer under the frictional surface is formed.The morphology and properties of the plastic deformation layer depend on specimen material,contact pressure and frictional shearing stress.In the plastic deformation layer,the phosphorous mass percent varies at different depth and results in different hardness.On the outer side of surface,the hardness is the biggest and the phosphorous mass percent is the highest.They become gradually small from outer side to inner side of the surface.展开更多
Anxiety disorder is one of the most common emotional disorders,but its pathogenesis re-mains unclear.Research has shown that iron deficiency is more common in people with emotional disorders and that these disorders c...Anxiety disorder is one of the most common emotional disorders,but its pathogenesis re-mains unclear.Research has shown that iron deficiency is more common in people with emotional disorders and that these disorders can improve after taking iron supple-ments.Many factors can cause anxiety disorders,includ-ing external stress,genetic factors,impaired neurodevel-opment,and abnormal monoamine metabolism.Studies have shown that abnormal monoamine metabolism and impaired neurodevelopment can contribute to the severity of emotional disorders.The synthesis of serotonin(5-HT)and dopamine(DA)require iron as a cofactor in the syn-thesis of monoamine metabolism,and the release of epi-nephrine(E)was potentially associated with labile iron in plasma.At the same time,iron is also directly involved in myelin synthesis as a cofactor in neural development.Therefore,iron maybe involved some of the main causes of the onset of anxiety disorders.展开更多
Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the...Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the material, the distrbutions of the effective strainrate and hydrostatic stress are obtained. Calculated results and the effect of die argles on thedeformation and ironing force are discussed. The companrson of calculated results with thcoe of ex-poriment shows a good agreement.展开更多
条带状铁建造(banded iron formation,BIF)是前寒武纪地层中广泛发育的一类富铁沉积岩,它在华北克拉通内广泛发育。在华北克拉通南缘的舞阳地区,晚太古代太华群铁山庙组BIF包含石英-磁铁矿和辉石-磁铁矿两种组合,前者的绝大部分磁铁矿...条带状铁建造(banded iron formation,BIF)是前寒武纪地层中广泛发育的一类富铁沉积岩,它在华北克拉通内广泛发育。在华北克拉通南缘的舞阳地区,晚太古代太华群铁山庙组BIF包含石英-磁铁矿和辉石-磁铁矿两种组合,前者的绝大部分磁铁矿颗粒均自形程度高、粒度粗大并常常紧密伴生有一定量的方解石。舞阳地区铁山庙组BIF的RAMAN,SEM,CL和EDS分析结果表明:石英-磁铁矿矿石中的磁铁矿自形程度最高、石英次之、方解石最低;方解石似条带的RAMAN分析结果指示其有序度、结晶程度沿条带的垂直方向无规律突变,明显不同于裂隙中后期热液流体沉淀形成的方解石脉;方解石发生了塑性流变并最终定位于石英和磁铁矿间的间隙内,其矿物的截面形状和展布特征明显受控于石英和磁铁矿并得到了石英颗粒间微裂隙内方解石的证实;方解石似条带的微区成份存在明显差异,这反映方解石经历了塑性流变及再次汇聚;在磁铁矿颗粒的汇聚及生长过程中,方解石充当了磁铁矿微颗粒迁移的媒介并得到了方解石中磁铁矿微颗粒局部富集现象的证实。展开更多
文摘The phenomenon of stress-induced recrystallization (SIR) and recrystallization- induced plasticity (RIP) in DT4 pure iron was investigated by means of hightemperature tensile test under a constant elastic stress and microstructural observation. It is shown that the macroscopic plastic flow of cold-rolled specimens, which occured during heating process under pre-loaded elastic stress, resulted from stressinduced recrystallization and recrystallization-induced plasticity. The characteristics and mechanism of this phenomenon were also preliminarily discussed.
文摘An incremental updated Lagrangian elasto-plastic finite element method(FEM) was employed to analyze the hole-flanging with the ironing of circulate plates using a pre-determined smaller hole at the center of the two-ply sheet metals. An extended rmin technique was employed such that each incremental step size can be determined not only by the yielding of an element Gaussian point, but also by the change under the boundary conditions of penetration, separation, and the alternation of the sliding-sticking state of friction along the tool-sheet interface. Two-ply sheet metals are generally composed of metals that have different mechanical properties. Thus, the forming process of these materials is complicated. A number of experiments and simulations were performed using a conical punch with a cone angle of 45°. The experimental results were compared with FEM-simulated results. It is found that using the elasto-plastic FEM can effectively predict the generation process of the deformed shape until unloading. The calculated sheet geometries and the relationship between punch load and punch travel are in good agreement with the experimental data.
基金Item Sponsored by Provincial Outstanding Youth Science Foundation of Henan in China(04120002100)Opening Foundationof State Key Laboratory of Solid Lubrication
文摘At room temperature,dry sliding wear tests were carried out using pin-on-disc test rig,in which the pin is made of vermicular iron and the disc is made of 40 Cr steel.The microstructures of the frictional surfaces for the pin specimens were investigated.Under the action of both frictional heat and frictional shearing stress,aplastic deformation layer under the frictional surface is formed.The morphology and properties of the plastic deformation layer depend on specimen material,contact pressure and frictional shearing stress.In the plastic deformation layer,the phosphorous mass percent varies at different depth and results in different hardness.On the outer side of surface,the hardness is the biggest and the phosphorous mass percent is the highest.They become gradually small from outer side to inner side of the surface.
文摘Anxiety disorder is one of the most common emotional disorders,but its pathogenesis re-mains unclear.Research has shown that iron deficiency is more common in people with emotional disorders and that these disorders can improve after taking iron supple-ments.Many factors can cause anxiety disorders,includ-ing external stress,genetic factors,impaired neurodevel-opment,and abnormal monoamine metabolism.Studies have shown that abnormal monoamine metabolism and impaired neurodevelopment can contribute to the severity of emotional disorders.The synthesis of serotonin(5-HT)and dopamine(DA)require iron as a cofactor in the syn-thesis of monoamine metabolism,and the release of epi-nephrine(E)was potentially associated with labile iron in plasma.At the same time,iron is also directly involved in myelin synthesis as a cofactor in neural development.Therefore,iron maybe involved some of the main causes of the onset of anxiety disorders.
文摘Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the material, the distrbutions of the effective strainrate and hydrostatic stress are obtained. Calculated results and the effect of die argles on thedeformation and ironing force are discussed. The companrson of calculated results with thcoe of ex-poriment shows a good agreement.
文摘条带状铁建造(banded iron formation,BIF)是前寒武纪地层中广泛发育的一类富铁沉积岩,它在华北克拉通内广泛发育。在华北克拉通南缘的舞阳地区,晚太古代太华群铁山庙组BIF包含石英-磁铁矿和辉石-磁铁矿两种组合,前者的绝大部分磁铁矿颗粒均自形程度高、粒度粗大并常常紧密伴生有一定量的方解石。舞阳地区铁山庙组BIF的RAMAN,SEM,CL和EDS分析结果表明:石英-磁铁矿矿石中的磁铁矿自形程度最高、石英次之、方解石最低;方解石似条带的RAMAN分析结果指示其有序度、结晶程度沿条带的垂直方向无规律突变,明显不同于裂隙中后期热液流体沉淀形成的方解石脉;方解石发生了塑性流变并最终定位于石英和磁铁矿间的间隙内,其矿物的截面形状和展布特征明显受控于石英和磁铁矿并得到了石英颗粒间微裂隙内方解石的证实;方解石似条带的微区成份存在明显差异,这反映方解石经历了塑性流变及再次汇聚;在磁铁矿颗粒的汇聚及生长过程中,方解石充当了磁铁矿微颗粒迁移的媒介并得到了方解石中磁铁矿微颗粒局部富集现象的证实。
