Papers by Keyword: Equivalent Strain

Abstract: The effects of rolling parameters on the broadwise deformation of the workpiece are analyzed by rigid-plastic finite element method. At the basis of better grasping the effective law on freedom broadwise deformation ,the effects of the Oval height and Oval width on the Forced /Restricted broadwise deformation in rolling process are analyzed. Considering the equivalent strain,the effects of the Oval height and Oval width are gotten again using the related strain data in the DEFORM-3D post-processing.

Abstract: This study introduces a process of high-pressure torsion (HPT) using ring samples and compares with the results of conventional disk HPT. Both types of HPT were conducted at room temperature on pure Al and pure Cu. The microhardness was measured along the diameters of the disks and rings. Microstructures were examined using transmission electron microscopy. When hardness values were plotted against equivalent strain, all data points fell on a single line for each material. There was a hardness maximum for pure Al but no such a maximum was present in pure Cu. In pure Al, many dislocations were visible within grains up to the equivalent strain corresponding to the hardness maximum but beyond this strain, grains with low dislocation density appear. All materials exhibited steady state where the hardness remains constant with respect to imposed equivalent strain. This study concludes that use of ring samples is effective as an alternative to the disk samples.

Abstract: It is believed that the shear deformation superimposed on rolling deformation accelerates grain refinement. However, it has not yet been completely understood whether the grain refinement is due to the increase in amount of equivalent strain, or the change in strain path. In the present study, three different strain paths in plane strain - (1) simple shear, (2) compression and (3) the combination of simple shear and compression - are introduced into 1100 aluminum sheet. The recrystallization behaviours are compared. Plane-strain compression was achieved by a normal rolling, while the simple shear was achieved by a continuous ECAE (conshearing). The combined strain path was achieved by the conshearing subsequently followed by the rolling. The same amount of the equivalent strain of 1.28 was accumulated in the three paths. The ratio of shear strain to compressive strain was varied by three levels in the combined strain process. After heat treatment, the material processed by the combined strain path gave a finer recrystallized grain size than both of the monotonic strain paths at either annealing temperature. The finest recrystallized grain size was obtained at the shear strain ratio of 0.6 to the total equivalent strain. It was found that the change in strain path was effective for introducing more new high-angle grain boundaries.

Abstract: Variant selection rule of plate martensite in a coarse-grained Fe-28.5at.%Ni alloy was investigated. Crystallographic analysis of martensite plates was carried out by electron back scattering diffraction (EBSD) analysis in a scanning electron microscope with a field emission type gun (FE-SEM). Certain variant selections were recognized for martensite plates in the Fe-28.5at.%Ni alloy. Equivalent strain, which was calculated from the shape strain of each variant, was used to evaluate the accommodation of the shear strain induced by martensite transformation. Variant selection was ruled not only by the shear strain accommodation but also by the ngle between habit planes of adjacent martensite plates.