Salt spray corrosion test was carried out on 6061 aluminum alloy, and quasi‐static tensile test at room temperature was carried out on the sample with universal testing machine. The effect of salt spray corrosion on the mechanical properties of 6061 aluminum alloy was studied by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electrochemistry. The corrosion rate of 6061 aluminum alloy was quantitatively characterized by different corrosion parameters. It was found that local corrosion of 6061 aluminum alloy occurred in salt spray environment, mainly pitting corrosion and intergranular corrosion. With the increase of corrosion time, the polarization resistance of 6061 aluminum alloy decreases, and the corrosion rate significantly increases. The average corrosion rate normalV‾d and the maximum corrosion rate Vdmax of 6061 aluminum alloy were characterized by corrosion weight loss and corrosion pit depth. And they can be transformed into each other. The mechanical properties of 6061 aluminum alloy were mainly affected by the depth of corrosion pit. With the increase of corrosion time, the tensile strength and fracture strain decreased, resulting in poor plasticity of the sample. At the same time, the change of elongation of 6061 aluminum alloy can be accurately predicted by the depth of corrosion pit.

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The effect of stress triaxiality on mechanical properties of 6061 aluminium alloy extruded profiles with different specimens was studied. Macroscopic mechanical property of the various specimen was got through universal testing machine. At the same time, stress triaxiality of different specimens was obtained using the method of finite element simulation. And then the fracture strain of each specimen was outputted by DIC. Fracture modes of 6061 aluminium alloy with different stress triaxiality were studied by SEM. The results show that taking tensile samples as comparison, the cross-sectional area of some notched specimens decreases and the peak load increases. Among them, the minimum cross-sectional area of the R5 central hole specimen is 20% smaller than that of the tensile sample, and the peak load is 28% larger. The fracture strain of the alloy increased with the decrease of stress triaxiality. For the same notch specimens, along the path direction, stress triaxiality of R5 notch specimens, R5 Center-hole specimens and R20 Arc notched specimens increased 47%, 17.8%, 25% respectively. According to the analysis of fracture morphology, the main fracture of 6061 aluminium alloy was ductile fracture. When the stress triaxiality is large, the dimples are small and sparsely distributed, and when the stress triaxiality is small, the dimple is large and evenly distributed. Finally, the Johnson-Cook model material parameters of 6061 aluminum alloy are fitted based on the tensile test results of different shapes of specimens, which can accurately simulate the elastic-plastic deformation and fracture instability of 6061 aluminum alloy under different stress states.

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.

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