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
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.
