Study On The Effect Of Grain Size On The Shear Band Behavior Of Fe-Fe And Fe-Ni Multilayered Composite Material

Multi-layered composite material attracts much attention due to its excellent combination of physical,chemical and mechanical property,which is attributed to the high density of boundaries and interfaces within the matrix.The dissimilarity of mechanic within each component leads to the stress incompatibility between the boundaries and interfaces.The incompatible shear stress causes the formation of shear band in the interface and significantly changes the performance of matrix material.The shear band is one of the most important deformation microstructure during rolling.Its size,density,angle and orientation are significantly affected by the initial grain size,and further decide the primary recrystallization texture.Up to date,much attention has been paid on the formation behavior of shear band in multilayered composite materials,but the influence mechanistic of interface for the formation of in-grain shear band has attracted little attention.In this thesis,the interface is supplied by the multilayered Fe-Fe and Fe-Ni composite materials.The effect of interface and grain size on the development process of shear band during cold rolling and annealing was investigated.The characterization of recrystallized nucleation orientation by EBSD provides direct comparison effect of heterogeneous and homogeneous interface on formation and orientation behavior of shear band.The general conclusions are listed as follows:(1)The quantity of shear band inside the Fe layer increases with initial grain size,and the primary recrystallization ? texture strengthens and y texture weakens.The involvement of FeFe interface facilitates the nucleation of shear band and suppresses the nucleation of grain boundary.Meanwhile,the nucleation texture in the shear band around interface is ? texture,but nucleation texture in the shear band away from interface is Goss texture.(2)The quantity of shear band in Fe-Ni composite increases and then decreases with annealing temperature.This result suggests that the formation of shear band is strongly affected by the initial grain size before rolling.The recrystallized ? texture is favored by increase of initial grain size,while ? texture is disfavored by increase of initial grain size.The tendency of primary recrystallization is coincided to the initial grain size but not the annealing temperature.(3)The proportion of ? texture increases and ? texture decreases with the increase of grain size in both heterogeneous and homogeneous interface material.The heterogeneous and homogeneous interfaces promote the formation of shear band,which in turn increase the quantity of ? texture and decrease the quantity of y texture.The additional stress at heterogeneous interface results in the deviation of orientation inside the shear band and weakens the ? texture.The general conclusions demonstrated the role of interface and grain size on the formation behavior of shear band in Fe-Fe and Fe-Ni multilayered composite materials.This work interprets the effect of heterogeneous and homogeneous interface on the formation of shear band,as well as the nucleation orientation inside,which offers theoretical and experimental support for designing the recrystallized texture by controlling the relationship between the grain size and interface.