Hot extrusions were performed to study the effects of extrusion conditions on microstructure, age-hardening behaviors and mechanical properties of Al–Zn–Mg alloy. The increasing of extrusion ratio from 10 to 35 effectively enhanced solid solubility of the as-extruded sheets. It accelerated the age-hardening response and significantly increased the number density of nanoscale matrix precipitates in peak-aged sheets. Higher extrusion ratio led to narrower extruded fibers in the sheets, while the extrusion temperature showed the opposite effect. The number of <111>//ED grains significantly decreased while that of <001>//ED grains increased a lot with increasing of extrusion ratio. Due to the differences in degree of deformation, grain size decreased monotonously from center to surface, thus contributing to the higher strength near the surface of peak-aged sheets than the center. The mechanical properties can be more homogeneous on cross section of the sheets by appropriately increasing extrusion ratio and temperature.
Extrusion ratio Extrusion temperature Al–Zn–Mg alloy Age-hardening behaviors Microstructure
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The authors acknowledge the financial supports by National Key R&D Program of China (No. 2016YFB1200504) and Strategic Priority Program of the Chinese Academy of Sciences (No. XDB22000000).
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