Transactions of Nanjing University of Aeronautics & Astronautics
Effect Analysis of High Strain Rate and Anisotropy on Tension-Compression Asymmetry of Aluminum Alloy 7050
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Abstract:
Using the devices of split Hopkinson tension bar (SHTB) and split Hopkinson pressure bar (SHPB), the dynamic tension and compression experiments in three typical forming directions (rolling direction （RD）, transverse direction （TD） and normal direction （ND）) were carried out at strain rates of 1 000, 2 000 and 4 000 s-1, respectively. From the microscopic point of view, the effect of strain rate and anisotropy on tension compression asymmetry of aviation aluminum alloy 7050 was studied by scanning electron microscope (SEM), metallographic microscope and electron backscatter diffraction (EBSD). The results showed that there was obvious asymmetry between tension and compression, especially that the yield strength of the material in tension was higher than that in compression. The asymmetry in the elastic stage of tension-compression was weaker and the asymmetry in the strengthening stage was stronger with the increase of strain rate. At the same strain rate, the changing trend of the flow stress was distinct under different orientations of tension and compression, which was related to the stress direction of the grains. According to EBSD grain orientation analysis and raw material texture pole figure analysis, it was found that the larger the difference in the degree of grain refinement during tension and compression, the larger the macro-flow stress difference.
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TG113
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