Microstructure and Mechanical Properties of 7056 Aluminum Alloy Thick Plates

Tensile tests, optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the mechanical properties and microstructure of 7056 aluminum alloy plates, which were rolled to a thickness of 40 mm. The results show that the microstructure of 7056 hot rolled plate is inhomogeneous in different layers. The second phase particles on the surface are distributed dispersively and their size is relatively small, while when they are concentrated at the center, the size is relatively large. From the surface to the center, the shear texture is gradually reduced. The content of the deformed texture in the center layer is the largest, and the difference between the cube textures in each layer is not significant. After solution treatment, the recrystallization texture increases and the shear texture decreases on the surface, and the deformed texture of the central layer increases. After aging, a large amount of homogeneous and fine eta phases appear in the surface layer and the center layer, while discontinuous precipitates and a certain width of precipitation-free zone can be observed at the grain boundaries. The optimal solution treatment of 40 mm thick 7056 plate is 470 degrees C for 3 h. After aging, the yield strength and the tensile strength of the surface layer are 605 MPa and 628 MPa, respectively, those of T/4 layer are 626 MPa and 643 MPa, respectively, and those of the center layer are 623 MPa and 639 MPa, respectively.