The experimental study of Bauschinger effect in Mn18Cr18N austenitic stainless steel was presented by compression-tensile cyclic loading tests with the prestrains ranging from 0.005 to 0.1,which was illustrated utiliz...The experimental study of Bauschinger effect in Mn18Cr18N austenitic stainless steel was presented by compression-tensile cyclic loading tests with the prestrains ranging from 0.005 to 0.1,which was illustrated utilizing stress-strain curves and analysed by TEM images from aspects of microstructural mechanisms.Moreover,the Bauschinger effect and its associated roundness phenomenon in reverse flow curve with respect to different cycles and cyclic strain amplitudes were evaluated in a quantitative manner.The experimental results indicate that Bauschinger effect is apparent during the test.At smaller cyclic strain amplitude,intergranular backstress is the main source of Bauschinger effect.With further increasing of cycles,dislocation density increases and dislocation movement is hindered in the reverse deformation.Therefore,Bauschinger effect is weakened to some extent.At large cyclic strain amplitude,backstress originating from the dislocation pile-up at grain boundaries and the continuous formation of deformation twins dominate the Bauschinger effect.In addition,the backstress results in the roundness of reverse curve during cyclic loading.The larger value ofΔεp*,the more obvious the roundness of the reverse curve,and the more significant the Bauschinger effect.展开更多
The plastic behaviors of thin metallic foils,including size effect,Bauschinger effect,and passivation effect,are studied under cyclic bending condition using the strain gradient visco-plasticity theory.The finite elem...The plastic behaviors of thin metallic foils,including size effect,Bauschinger effect,and passivation effect,are studied under cyclic bending condition using the strain gradient visco-plasticity theory.The finite element simulations are performed on the cyclic bending of the elasto-viscoplastic thin foils with passivated and unpassivated surfaces.The study is also conducted on the transition from a passivated surface to an unpassivated one.The roles of the dissipative and energetic gradient terms are emphasized.From the results,it is found that the dissipative gradient terms increase the yield strength,while the energetic gradient terms increase the strain hardening,resulting in an anomalous Bauschinger effect.Further,it is observed that the surface passivation effect increases both the normalized bending moment at initial yielding and strain hardening.The comparison between the numerical results of cases with and without passivation demonstrates that the switching of boundary conditions significantly affects the plastic behavior of the foils under cyclic bending.展开更多
基金the National Natural Science Foundation of China(No.51575372)the Science and Technology Research Plan(Industrial)Project of Shanxi Province,China(No.201603D121006-2)+1 种基金the Start-up Fund for Scientific Research of Taiyuan University of Science and Technology(No.20172011)the Fund for Shanxi Key Subjects Construction。
文摘The experimental study of Bauschinger effect in Mn18Cr18N austenitic stainless steel was presented by compression-tensile cyclic loading tests with the prestrains ranging from 0.005 to 0.1,which was illustrated utilizing stress-strain curves and analysed by TEM images from aspects of microstructural mechanisms.Moreover,the Bauschinger effect and its associated roundness phenomenon in reverse flow curve with respect to different cycles and cyclic strain amplitudes were evaluated in a quantitative manner.The experimental results indicate that Bauschinger effect is apparent during the test.At smaller cyclic strain amplitude,intergranular backstress is the main source of Bauschinger effect.With further increasing of cycles,dislocation density increases and dislocation movement is hindered in the reverse deformation.Therefore,Bauschinger effect is weakened to some extent.At large cyclic strain amplitude,backstress originating from the dislocation pile-up at grain boundaries and the continuous formation of deformation twins dominate the Bauschinger effect.In addition,the backstress results in the roundness of reverse curve during cyclic loading.The larger value ofΔεp*,the more obvious the roundness of the reverse curve,and the more significant the Bauschinger effect.
基金supported by the National Natural Science Foundation of China under Grant 11702103,and the Young Top-notch Talent Cultivation Program of Hubei Province.
文摘The plastic behaviors of thin metallic foils,including size effect,Bauschinger effect,and passivation effect,are studied under cyclic bending condition using the strain gradient visco-plasticity theory.The finite element simulations are performed on the cyclic bending of the elasto-viscoplastic thin foils with passivated and unpassivated surfaces.The study is also conducted on the transition from a passivated surface to an unpassivated one.The roles of the dissipative and energetic gradient terms are emphasized.From the results,it is found that the dissipative gradient terms increase the yield strength,while the energetic gradient terms increase the strain hardening,resulting in an anomalous Bauschinger effect.Further,it is observed that the surface passivation effect increases both the normalized bending moment at initial yielding and strain hardening.The comparison between the numerical results of cases with and without passivation demonstrates that the switching of boundary conditions significantly affects the plastic behavior of the foils under cyclic bending.
