The effects of Cu on stacking fault energy,dislocation slip,mechanical twinning,and strain hardening in Fe–20Mn–1.3C twinning-induced plasticity（TWIP） steels were systematically investigated.The stacking fault ene...The effects of Cu on stacking fault energy,dislocation slip,mechanical twinning,and strain hardening in Fe–20Mn–1.3C twinning-induced plasticity（TWIP） steels were systematically investigated.The stacking fault energy was raised with an average slope of 2 mJ/m2 per 1 wt% Cu.The Fe–20Mn–1.3C–3Cu steel exhibited superior tensile properties,with the ultimate tensile strength reached at 2.27 GPa and elongation up to 96.9% owing to the high strain hardening that occurred.To examine the mechanism of this high strain hardening,dislocation density determination by XRD was calculated.The dislocation density increased with the increasing strain,and the addition of Cu resulted in a decrease in the dislocation density.A comparison of the strain-hardening behavior of Fe–20Mn–1.3C and Fe–20Mn–1.3C–3Cu TWIP steels was made in terms of modified Crussard–Jaoul（C–J） analysis and microstructural observations.Especially at low strains,the contributions of all the relevant deformation mechanisms—slip,twinning,and dynamic strain aging—were quantitatively evaluated.The analysis revealed that the dislocation storage was the leading factor to the increase of the strain hardening,while dynamic strain aging was a minor contributor to strain hardening.Twinning,which interacted with the matrix,acted as an effective barrier to dislocation motion.展开更多
The present study focuses on an inextensible beam and its relevant inertia nonlinearity,which are essentially distinct from the commonly treated extensible beam that is dominated by the geometric nonlinearity.Explicit...The present study focuses on an inextensible beam and its relevant inertia nonlinearity,which are essentially distinct from the commonly treated extensible beam that is dominated by the geometric nonlinearity.Explicitly,by considering a weakly constrained or free end(in the longitudinal direction),the inextensibility assumption and inertial nonlinearity(with and without an initial curvature)are introduced.For a straight beam,a multi-scale analysis of hardening/softening dynamics reveals the effects of the end stiffness/mass.Extending the straight scenario,a refined inextensible curved beam model is further proposed,accounting for both its inertial nonlinearity and geometric nonlinearity induced by the initial curvature.The numerical results for the frequency responses are also presented to illustrate the dynamic effects of the initial curvature and axial constraint,i.e.,the end mass and end stiffness.展开更多
基金financially supported by the Major Project for Industry-University-Research of Fujian Province,China (No.2011H6012)the Natural Science Foundation of Fujian Province,China (No.2011J01292)the Key Project of Fujian Provincial Department of Science and Technology (No.2011H0001)
文摘The effects of Cu on stacking fault energy,dislocation slip,mechanical twinning,and strain hardening in Fe–20Mn–1.3C twinning-induced plasticity（TWIP） steels were systematically investigated.The stacking fault energy was raised with an average slope of 2 mJ/m2 per 1 wt% Cu.The Fe–20Mn–1.3C–3Cu steel exhibited superior tensile properties,with the ultimate tensile strength reached at 2.27 GPa and elongation up to 96.9% owing to the high strain hardening that occurred.To examine the mechanism of this high strain hardening,dislocation density determination by XRD was calculated.The dislocation density increased with the increasing strain,and the addition of Cu resulted in a decrease in the dislocation density.A comparison of the strain-hardening behavior of Fe–20Mn–1.3C and Fe–20Mn–1.3C–3Cu TWIP steels was made in terms of modified Crussard–Jaoul（C–J） analysis and microstructural observations.Especially at low strains,the contributions of all the relevant deformation mechanisms—slip,twinning,and dynamic strain aging—were quantitatively evaluated.The analysis revealed that the dislocation storage was the leading factor to the increase of the strain hardening,while dynamic strain aging was a minor contributor to strain hardening.Twinning,which interacted with the matrix,acted as an effective barrier to dislocation motion.
基金Project supported by the National Natural Science Foundation of China(Nos.12372007,12432001,12372006,and 11972151)。
文摘The present study focuses on an inextensible beam and its relevant inertia nonlinearity,which are essentially distinct from the commonly treated extensible beam that is dominated by the geometric nonlinearity.Explicitly,by considering a weakly constrained or free end(in the longitudinal direction),the inextensibility assumption and inertial nonlinearity(with and without an initial curvature)are introduced.For a straight beam,a multi-scale analysis of hardening/softening dynamics reveals the effects of the end stiffness/mass.Extending the straight scenario,a refined inextensible curved beam model is further proposed,accounting for both its inertial nonlinearity and geometric nonlinearity induced by the initial curvature.The numerical results for the frequency responses are also presented to illustrate the dynamic effects of the initial curvature and axial constraint,i.e.,the end mass and end stiffness.
