Abstract:The impact of cold rolling deformation, which was introduced after solid solution and before aging treatment, on microstructure evolution and mechanical properties of the as-extruded spray formed Al-9.8Zn-2.3Mg-1.73Cu- 0.13Cr (wt.%) alloy, was investigated. SEM, TEM, and EBSD were used to analyze the microstructures, and tensile tests were conducted to assess mechanical properties. The results indicate that the D1-T6 sample, subjected to 25% cold rolling deformation, exhibits finer grains (3.35 μm) compared to the D0-T6 sample (grain size of 4.23 μm) without cold rolling. Cold rolling refines the grains that grow in solution treatment. Due to the combined effects of finer and more dispersed precipitates, higher dislocation density and smaller grains, the yield strength and ultimate tensile strength of the D1-T6 sample can reach 663 and 737 MPa, respectively. In comparison to the as-extruded and D0-T6 samples, the yield strength of the D1-T6 sample increases by 415 and 92 MPa, respectively.

Key words: Al-Zn-Mg-Cu alloy; spray forming; microstructure evolution; mechanical properties; strengthening mechanism