Study on Al/Mg/Al sheet fabricated by combination of porthole die co-extrusion and subsequent hot rolling

Al/Mg/Al sheet was fabricated by the proposed porthole die co-extrusion and subsequent hot rolling (PCE-R) method. The intermetallic compounds of beta-Al3Mg2 and gamma-Mg17Al12 were formed in transition layer after PCE-R process, and the thicknesses of beta and gamma layers became larger at higher rolling temperature or higher reduction ratio. Partial dynamic recrystallization (DRX) occurred in Al layer, and Al layer mainly consisted of shear-typed {111} fiber textures. However, if the rolling reduction is as high as 75%, Al layer exhibited quite different texture components. Mg layer consisted of fine equiaxed grains and several elongated grains, implying the occurrence of near complete DRX. With the increase of rolling temperature or reduction ratio, the number of Mg17Al12 particles in Mg layer was reduced, resulting into larger grain size. Mg layer had strong basal plane texture with c-axis parallel to transverse direction. Al/Mg/Al sheet rolled at 300 degrees C with 65% reduction exhibited two stress-drop fracture mechanism during tensile test, and it showed excellent tensile strength of 149 MPa, and elongation of 0.13. However, Al/Mg/Al sheet rolled with 75% reduction had inferior tensile properties due to the existence of some cracks after rolling. (C) 2019 Elsevier B.V. All rights reserved.