抄録
In their previous paper, the authors have reported the study on the relation between the change in half-value breadth of X-ray diffraction line and the orientation factor μ of the reflecting crystals under cyclic or static stress of relatively low magnitude (σ_??_10kg/mm2). (Whereτs=μσ; σ is applied stress and τs is resolved shear stress). It was found that, under cyclic stress the half-value breadth showed great change in proportion to the values of μ of the grains, that is, slip occurred preferentially in the favourably oriented crystals. Under static stress, however, it was found that the change in half-value breadth was almost the same irrespective of the μ-values of the crystals. This may be understood from the mutual restriction of grains during the static straining.
In the present paper, then, the changes in half-value breadth are investigated under cyclic and static stresses of relatively high magnitude (σ_??_10mg/mm2). It was found that, in contrast to the previous paper, the changes in half-value breadth could be interpreted more properly in terms of the orientation dependence of the work hardening rate g of corresponding single crystal, than orientation factor μ. This suggests that the orientation dependence of the work hardening rate of crystals in polycrystalline aggregates is similar to that of single crystals. It can be concluded that; (1) the fatigue mechanism of Cu is different depending of applied stress levels, (2) the orientation dependence of the work hardening rate of the crystals must be taken into account in order to get a relevant model of polycrystalline aggregates of Cu.
