| dc.description.abstract | In this study, the AA7005 aluminum alloy hot-extruded round bar in F state was used as the raw material, and it was subjected to stress relief annealing, forging and T6 treatment successively. Compression is carried out in the direction perpendicular to the extrusion; the tensile test bar used for testing mechanical properties is made in accordance with the specifications of ASTM-E8, and the direction of the test is parallel to the extrusion direction of the initial extrusion, and finally through the weaving. microstructural properties such as structure and grain boundaries to explore the reasons for the differences in mechanical properties. In this study, the extrusion direction is defined as the Y axis, the forging direction is defined as the Z axis, and the main analysis plane is the Y-Z plane. In addition, this study adopts a staged analysis, and the whole post-forging heat treatment process is divided into pre-forging, post-forging and heat treatment. The latter three stages are used to understand the causes of microstructural differences; this study uses optical microscopy (OM), electron back scatter diffraction (EBSD) for analysis, and obtains grain shape, grain boundary angle ratio, grain boundary total length and The result of the texture state. The analysis results show that the extrusion process will divide the material into three parts from the surface layer to the center according to different mechanical states, namely the coarse grain layer, the transition layer and the fibrous grain layer. The fibrous crystal layer is partially recrystallized and retains the band-like structure formed during the extrusion process, while the cold-forged forgings will be completely recrystallized. V The area tested by the tensile test bar corresponds to the structural state of the fibrous crystal layer, and under different forging process conditions, the mechanical properties of the four groups of forgings all meet the requirements of the specification (YS≧290 MPa, UTS≧350 MPa, TEL≧ 13%), in which the difference in mechanical properties of each forging is related to different microstructure indicators, the YS value is related to the texture in the Y-axis direction, the <111> texture proportion is positively related to the YS value, and the UTS and Y-Z planes are related to The total grain boundary length is positively correlated with the TEL, and the TEL is negatively correlated with the aspect ratio of the grains in the X-Z plane. | en_US |