CAJ | 학술논문

为了研究铝合金7075-T651的流变应力变化特征,在高温分离式霍普金森压杆装置上对圆柱试样进行了温度范围25~400℃及应变率范围600~12000 s?1的动态压缩试验.结果表明:铝合金7075-T651的流变应力对应变率不敏感,对温度有较强的敏感性.总体上,流变应力随温度的升高而减小,但在350~400℃时流变应力差别很小.在高应变速率时,当应变超过一定水平时,应力出现急剧减小,材料发生失效.通过变形后试样的微观组织观察可以发现,应变速率较高时出现绝热剪切带是材料流变应力急剧减小的主要原因.在实验数据基础上,建立了一个基于物理概念的铝合金7075-T651本构模型预测其流变应力,与实验对比表明,所建立的本构模型在较宽的温度和应变速率范围内能够很好地预测铝合金7075-T651的流变应力.
위료연구려합금7075-T651적류변응력변화특정,재고온분리식곽보금삼압간장치상대원주시양진행료온도범위25~400℃급응변솔범위600~12000 s?1적동태압축시험.결과표명:려합금7075-T651적류변응력대응변솔불민감,대온도유교강적민감성.총체상,류변응력수온도적승고이감소,단재350~400℃시류변응력차별흔소.재고응변속솔시,당응변초과일정수평시,응력출현급극감소,재료발생실효.통과변형후시양적미관조직관찰가이발현,응변속솔교고시출현절열전절대시재료류변응력급극감소적주요원인.재실험수거기출상,건립료일개기우물리개념적려합금7075-T651본구모형예측기류변응력,여실험대비표명,소건립적본구모형재교관적온도화응변속솔범위내능구흔호지예측려합금7075-T651적류변응력.
@@@@To understand the flow stress characteristics of aluminum 7075-T651, dynamic compression tests during the temperature range of 25?400℃and strain rate range of 600?12 000 s?1 were performed on cylindrical samples using SHPB technique. The results show that the flow stress of aluminum 7075-T651 is strongly sensitive to temperature compared with strain rate, the flow stress reduces with the increase of temperature. There is a temperature range between 350?400℃where the flow stress doesn’t depend on temperature, showing little difference. At high strain rate when the strain exceeds one certain level, the flow stress decreases sharply and the sample fails. Through the observation of cross-section microstructure of deformed sample, the shear band is responsible for the rapid reduction of flow stress. Finally based on experimental data, a physically based constitutive model is given to depict the flow stress of the aluminum. The model predictions are compared with the results of experiments. Good agreement between the theoretical predictions and experimental results is obtained. The given constitutive model can predict the flow stress of aluminum 7075-T651 in a wide range of temperatures and strain rates.