2016 年 82 巻 834 号 p. 15-00396
High-strength, light-weight metal materials are required to improve safety and reduce transportation cost. Ultrafine-grained metals produced by severe plastic deformation have attracted interest as high-strength materials. In the case of ultrafine-grained metals, strong rolling texture induced by severe plastic deformation influences anisotropy of yield surface remarkably. However, measurement for the yield surface of ultrafine-grained metals requires a great deal of labor. A computational model predicting the yield surfaces of ultrafine-grained metals is desired in the field of materials science and engineering. In this study, using results obtained by electron backscatter diffraction, information on crystal orientation and shape of grains are introduced into a computational model for multiscale crystal plasticity simulation considering the effects of grain boundaries and dislocation sources. Finite element simulations for polycrystal of aluminum under biaxial tension are performed in order to predict yield surface of the ultrafine-grained metal. A genetic algorithm is used to derive the higher-ordered yield function of ultrafine-grained metal. The effects of crystal orientation on the macroscopic mechanical properties of the ultrafine-grained metals are investigated by the obtained numerical results.
