通过扭转变形对6061-T651铝合金进行强化,扭转角度为90°,180°,360°,并对扭转前后的样品进行准静态和动态压缩性能研究。结果表明:随着扭转角度的增加,样品的晶粒尺寸先保持不变,然后开始减小;而Kernel平均取向差(Kernel ...通过扭转变形对6061-T651铝合金进行强化,扭转角度为90°,180°,360°,并对扭转前后的样品进行准静态和动态压缩性能研究。结果表明:随着扭转角度的增加,样品的晶粒尺寸先保持不变,然后开始减小;而Kernel平均取向差(Kernel average misorientation,KAM)却随着扭转角度的增加持续增大。准静态和动态压缩实验显示,随着扭转角度的增加,样品材料的屈服强度稍有提高。在扭转角度相同的条件下,动态屈服强度明显高于准静态下的屈服强度。应变率实验显示样品的屈服强度随着应变率的增加而增大,但是相比于未扭转样品,扭转360°样品的应变率效应显著降低。基于实验数据,拟合了Cowper-Symonds本构模型中的参量,该模型得到的应力-应变曲线与实验结果能够较好地吻合。展开更多
Plate-impact experiments have been carried out to examine the effect of grain size and grain arrangement on the damage evolution of ultrapure aluminum. Two groups of samples, ＂cross-cut＂ and ＂longitudinal-cut,＂ ar...Plate-impact experiments have been carried out to examine the effect of grain size and grain arrangement on the damage evolution of ultrapure aluminum. Two groups of samples, ＂cross-cut＂ and ＂longitudinal-cut,＂ are obtained from the rolled aluminum rod along different directions. The peak compressive stress is approximately 1.25 GPa–1.61 GPa, which can cause incipient spall damage that is correlated to the material microstructure. The metallographic analyses of all recovered samples show that nearly all damage nucleates at the grain boundaries, especially those with larger curvature. Moreover, under lower shock stress, the spall strength of the ＂longitudinal-cut＂ sample is smaller than that of the ＂crosscut＂ sample, because the different grain sizes and arrangement of the two samples cause different nucleation, growth, and coalescence processes. In this study, the difference in the damage distribution between ＂longitudinal-cut＂ and ＂cross-cut＂ samples and the causes for this difference under lower shock-loading conditions are also analyzed by both qualitative and semi-quantitative methods. It is very important for these conclusions to establish a reasonable and perfect equation of damage evolution for ductile metals.展开更多
文摘通过扭转变形对6061-T651铝合金进行强化,扭转角度为90°,180°,360°,并对扭转前后的样品进行准静态和动态压缩性能研究。结果表明:随着扭转角度的增加,样品的晶粒尺寸先保持不变,然后开始减小;而Kernel平均取向差(Kernel average misorientation,KAM)却随着扭转角度的增加持续增大。准静态和动态压缩实验显示,随着扭转角度的增加,样品材料的屈服强度稍有提高。在扭转角度相同的条件下,动态屈服强度明显高于准静态下的屈服强度。应变率实验显示样品的屈服强度随着应变率的增加而增大,但是相比于未扭转样品,扭转360°样品的应变率效应显著降低。基于实验数据,拟合了Cowper-Symonds本构模型中的参量,该模型得到的应力-应变曲线与实验结果能够较好地吻合。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 1117221 and 11072119)the Defense Industrial Technology Development Program and the Fundamental Research Funds for the Central Universities (Grant Nos. B1520110003 and 2012-Ia-004)
文摘Plate-impact experiments have been carried out to examine the effect of grain size and grain arrangement on the damage evolution of ultrapure aluminum. Two groups of samples, ＂cross-cut＂ and ＂longitudinal-cut,＂ are obtained from the rolled aluminum rod along different directions. The peak compressive stress is approximately 1.25 GPa–1.61 GPa, which can cause incipient spall damage that is correlated to the material microstructure. The metallographic analyses of all recovered samples show that nearly all damage nucleates at the grain boundaries, especially those with larger curvature. Moreover, under lower shock stress, the spall strength of the ＂longitudinal-cut＂ sample is smaller than that of the ＂crosscut＂ sample, because the different grain sizes and arrangement of the two samples cause different nucleation, growth, and coalescence processes. In this study, the difference in the damage distribution between ＂longitudinal-cut＂ and ＂cross-cut＂ samples and the causes for this difference under lower shock-loading conditions are also analyzed by both qualitative and semi-quantitative methods. It is very important for these conclusions to establish a reasonable and perfect equation of damage evolution for ductile metals.
