Microstructure, texture and mechanical properties of Al–Zn–Mg–Zr cylindrical part with thin-wall and high-rib formed by integral-accuracy-extrusion

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2023-10, Vol.886, p.145725, Article 145725
• Main Authors: Wang, Xu, Wang, Duanzhi, Zhao, Yongxing, Shao, Hongbang, Huang, Yuanchun, Huang, Changqing
• Format: Article
• Language: English
• Subjects: Al–Zn–Mg–Zr alloy; Cylindrical part; Integral-accuracy-extrusion; Recrystallization behavior; Strengthening and toughening mechanism; Texture evolution
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2023.145725

The complex section cylindrical part with thin-wall and high-rib was obtained through integral-accuracy-extrusion, and the microstructure evolution, recrystallization behavior, texture configuration and strengthening and toughening mechanism were investigated. Samples of different positions all exhibit the microstructure of predominant elongated grains along extrusion direction (ED) surrounded by fine equiaxed grains, but the width of elongated grains in the rib is higher than that in the thin-wall. Except for particle-stimulated nucleation (PSN) mechanism due to the MgZn2, the dominant recrystallization mechanism of all samples should be discontinuous dynamic recrystallization (DDRX), and the parent grains with the orientation of (001)//ED are more susceptible to recrystallization than other orientations. Additionally, more prone to continuous dynamic recrystallization (CDRX) results in a higher recrystallization fraction and a lesser average grain size in the thin-wall. Samples in the rib are dominated by strong copper-type texture, showing the feature of deformation texture; as for sample in the thin-wall, a high strength of Cube texture is displayed. The ultimate tensile strength (UTS) of the sample in the rib is 20 MPa higher than that in the thin-wall, which is mainly attributed to texture strengthening caused by hard orientation grains with smaller Schmid factor (SF), but the elongation of sample in the thin-wall is 30% higher than the rib (15.1% vs 11.6%), showing a superior plasticity, which is related to higher SF, higher recrystallization fraction and more homogeneous microstructure. This research will theoretically guide the manufacture of high-performance complex section Al–Zn–Mg–Zr cylindrical part with thin-wall and high-rib.