Al–Zn–Mg–Cu合金押出材の集合組織と強度に及ぼす断面形状の影響

抄録

The effect of the extrusion shape on the strength of Al–Zn–Mg–Cu alloys was investigated by measurement of the orientation distribution function (ODF) and the mechanical properties. For an extruded bar having an aspect ratio from 1 to 5, the strength in the longitudinal direction decreased with the increasing aspect ratio. For an extruded bar having an aspect ratio from 5 to 20, the strength in the longitudinal direction was nearly constant. There were no significant differences in the dispersion of fine precipitates and the electrical conductivity between the extrusion shapes. However, extrusion shapes influenced the crystallographic texture. For the extrusion shape having an aspect ratio of 1, the major orientation in the longitudinal direction was 〈111〉, for the extrusion shapes having an aspect ratio from 1 to 3, the major orientation changed from 〈111〉to 〈211〉, and for the extrusion shapes having an aspect ratio of 5 and more, the major orientation was 〈211〉. Therefore, the strength depended on Taylor's factor, or difficulty of slip toward the stress axis.