| 6061 is the main of 6XXX series of aluminum alloys,which has been gradually utilized in engineering structures due to its advantages of light weight,high strength,good ductility,easy processing and good corrosion resistance,etc.In addition to bear the single condition such as dynamic load and high temperature and so on,the structure members will inevitably be subjected to coupling effects by multiple disaster such as high temperature,impact or explosive load during their service life.Compared with the single conditions,the mechanical properties of materials become more complex under the coupling effects of high temperature and impact.At present,there are several studies on the conventional static,dynamic and high-temperature properties of 6061 aluminum alloy.There are few studies on the performance under coupled high strain rate and high temperature,and no prediction model has been proposed.Therefore,this paper will investigate the mechanical properties of 6061 aluminum alloy at different strain rates and temperatures.Besides,the corresponding constitutive relationship model was established.The main contents are as follows:(1)The quasi-static tensile and high-temperature quasi-static compression tests of 6061 aluminum alloy were performed,and the basic mechanical properties of this alloy were obtained.The results show that the 6061 aluminum alloy exhibits obvious brittle failure during the quasi-static tensile test,and the temperature softening phenomenon appeared during the high-temperature quasi-static compression test.The higher the temperature,the more obvious the softening effect.(2)The dynamic compression test using hopkinson pressure bar apparatus with synchronous assembly heating system was conducting,considering the parameters of strain rate and temperature.The stress-strain curves were obtained under high strain rate and different heating temperatures,and the influence of mechanical properties for the parameters were mainly analyzed.The results show that the 6061 aluminum alloy exhibits a weak strain-rate strengthening effect at high strain rate.At high temperature,it presents a high lever effect of temperature softening.Compared with the strain-rate strengthening effect,thermal softening has more significant effect on the mechanical properties of 6061 aluminum alloy.(3)According to the stress variation of 6061 aluminum alloy under different conditions,a constitutive model considering the parameters of strain rate and temperature is proposed.The insignificant difference was observed between the predicted model and test results,which indicating that the model can effectively describe the mechanical characteristics of strain hardening,strain-rate strengthening and temperature softening effects of 6061 aluminum alloy. |
