An X-Ray Study on the Plastic Deformation of Polycrystalline Metals Subjected to Cyclic Stressing

Abstract

A series of studies have hitherto been made on the influence of strain history on the plastic deformation of polycrystalline metals, and as an instance thereof is given in the present paper, a report of investigation that was made from the viewpoint of crystal plasticity, on the behavior of plastic deformation of metals subjected to low-cycle pulsating stresses. In order to discuss the structural change of the material under low-cycle stressing, the experimental measurement of misorientation was performed in the course of low-cycle tensile stressing on the coarse-grained sheet specimen by application of X-ray back-reflection Laue method. From the present analytical and experimental studies, the following conclusions have been obtained:(1) The measured value of misorientation in the coarsed grain of the specimen has increased with advanced number of cycle of low-cycle stressing. Moreover, the change of misorientation in the polycrystalline structural grain under cyclic stressing is larger than that in the monocrystalline structural grain.(2) The misorientation in the polycrystalline structural grain is dependent not only on the orientation factor of each diffraction plane but also on the Schmid factor of the grain at an early stage of cyclic stressing. But these dependency has decreased at the stage of an advanced cycles.(3) The variation in distribution of misorientation in the polycrystalline structural grain is remarkable at the stage of an advanced cycles in its favor in comparison with that in the monocrystalline structural grain.