2020 Volume 61 Issue 1 Pages 104-110
This study investigated the influence of the solute concentration and iron on the recrystallization texture formation of an A6063 alloy extruded with the preferred orientation, a commercially available cast A6063 alloy, an alloy containing no Fe, an alloy containing varying amounts of Mg and Si, and the extruded material. The obtained extruded material, the material structure in the extrusion chamber, and the crystal orientation were evaluated using scanning electron microscopy combined with electron backscattering pattern (SEM-EBSP). In the cross-section of the texture of the extruded material, the main orientation was cube; while the main orientation on the surface was crystal grains with a TD // 〈111〉 relationship, such as the Brass orientation and the S orientation. In the alloy that did not contain Fe, the accumulation of cube-oriented grains increased with increasing amounts of Mg and Si. Furthermore, in the surface texture, the accumulation in the direction of TD // 〈111〉 become weak with increasing amounts of Mg and Si. In the alloy containing Fe, the size of the recrystallized grains decreased after extrusion; here, a decrease in the cube-oriented grains and an increase in the brass-like-oriented grains were observed. The structure in the extrusion chamber confirmed that the cube orientation, which is the main orientation after extrusion, barely existed in the chamber, and is formed in front of the extrusion-bearing inlet. It was thereby inferred that the texture of the extruded material is formed during processing and recrystallization from the extrusion-bearing inlet to the bearing portion. During the recrystallization texture formation of the extruded material, Fe forms an Al–Fe–Si compound in the material to suppress recrystallization grain growth. Consequently, expansion of the cube-oriented recrystallized grains that preferentially grow during extrusion is suppressed, and the proportion of these grains is reduced. This suggests that Mg and Si are solid-solved in the Al matrix to reduce the stacking fault energy and to increase the strain accumulation energy during extrusion processing. This in turn accelerates the formation and expansion of cube-oriented grains.
