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In the ultrasonic-assisted metal forming process, the dislocations within the material are easier to move due to the absorption of ultrasonic energy, which can effectively promote material flow and improve the formability of components, this phenomenon is called the ultrasonic softening effect. The ultrasonic softening effect is generally treated as homogeneous at the whole materials for simplicity, while the attenuation of the ultrasonic energy along the propagation direction will bring inhomogeneous distribution of softening degree. In addition, the absorption of the ultrasonic energy by material is also affected by the dislocation movements in the metal plastic processing procedure, resulting in the variation of the ultrasonic attenuation characteristics in the material with the plastic deformation, the current research has little concerned it. In this paper, the ultrasonic attenuation properties in 2219-O aluminum alloy with plastic strain were investigated. The influence of the dislocations and the dislocation movements caused by plastic deformation on the ultrasonic attenuation was characterized. The pre-strain specimen was designed to indicate the degree of plastic deformation of the material, and the specimen thickness direction was defined as the propagation direction of the ultrasonic energy. The experimental results and the microstructure observation showed that the absorption of ultrasonic energy by the material increases firstly and then decreases with the plastic strain increasing, which is related to the evolution of movable dislocations within the material. In order to accurately describe the ultrasonic energy attenuation characteristics in plastic deformation, the hardening equation of 2219-O aluminum alloy considering ultrasonic propagation distance and plastic strain was built and the model accuracy was verified based on the experimental data.

The mechanical properties and bending deformation behaviors of homogenization treated (HT), solution treated (ST), natural aging (NA) treated and T6 6061 aluminum alloy sheets were investigated by tensile tests and three-point bending tests, respectively. The results showed that the heat treatment conditions have a significant impact on mechanical properties and bending characteristic. Bending radius and thickness of the HT alloy is the highest, and its springback angle is the lowest. However, the deformation mechanism of T6-8h alloy is just the opposite. The bending characteristics are attributed to the combined effects of yield strength, strain-hardening exponent and coefficient of the neutral layer. The simulation results are in good agreement with the experiment.

The effect of through-holes position on deformation behaviors and energy absorption of 6063 aluminum alloy with thin-walled structure, taking the same number and different positions of through-holes, will be investigated by quasi-static axial compression using universal testing machine. The experimental results show that the compression behavior of thin-walled structure specimens can be significantly improved by properly opening through-holes and selecting appropriate locations. Based on the experimental data, the fluctuation degree of sample load was reduced. The stability of compression deformation was improved. The first peak load was reduced. And the energy absorption performance of the specimens was improved.

The stamping deformation and springback of the 6061 aluminum alloy sheets under different heat treatment conditions were investigated by three-point bending tests. A validated reliable finite element (FE) model was used to further reveal the springback mechanism. It was found that the heat treatment conditions have great influence on the stamping deformation and springback of 6061 aluminum alloy sheets. The most severe local deformation occurred at the punch position of the T6–8 h alloy sheet, showing minimum bending radius and thickness. However, the bending radius and thickness of the homogenization treated (HT) alloy sheet were maximum, resulting from more materials participate in bending deformation. The HT and solution treated (ST) alloys exhibited higher stamping performance than that of the natural aged (NA) and T6 alloys. The material strength of the T6 alloys can be improved by aging time, motivating greater springback and neutral layer offset. The springback and neutral layer offset of the T6–8 h alloy sheet were the highest, while the HT alloy sheet was the lowest. Furthermore, the effect of material parameters on stamping deformation and springback of sheet was studied by combining with theoretical analysis and experimental results. The research showed that the bending radius and thickness of the sheet in the fillet region increase with the increase of strain-hardening exponent and elongation and with the decrease of yield ratio. After unloading, springback angle and radius increase with the increase of yield strength and strength factor and with the decrease of strain-hardening exponent. These achievements may serve as a guideline for enhancing stamping performance and reducing springback of the aluminum alloy sheet in bending process.