6013-T4铝合金不同温度下的动态流变应力及组织演变

摘要

The dynamic compression tests of 6013-T4 aluminum alloy were conducted at the temperatures of 25 ℃,100 ℃,200 ℃,300 ℃ and 400 ℃,at the strain rates of 1 000 s-1,2 000 s-1,3 000 s-1,4 000 s-1 and 5 000 s-1 by split Hopkinson pressure bar (SHPB),the true stress-true strain curves were obtained.The microstructure evolution of dynamic compression test specimens under different test conditions was observed by means of transmission electron microscopy (TEM).Results show that the flow stress of 6013 aluminum alloy has weak sensitivity to the strain rate but strong sensitivity to temperature.The effect of strain rate and temperature on microstructure of 6013 aluminum alloy is remarkable,the dislocation density increased with the increase of strain rate and decreased with the increase of temperature.Based on the experimental data,the constitutive parameters of the Johnson-Cook model of 6013 aluminum alloy were obtained and the constitutive model was built.The constitutive model can well predict the flow stress of 6013 aluminum alloy compared with the experimental results.%采用分离式霍普金森(SHPB)压杆装置进行6013-T4铝合金动态压缩试验,获得温度为25℃、100℃、200℃、300℃、400℃,应变速率为1 000 s-1、2 000 s-1、3 000 s-1、4 000 s-1、5 000 s-1条件下材料的真应力-真应变曲线,并通过透射电子显微镜(TEM)观测了6013-T4铝合金在不同变形条件下的组织演变.结果表明:6013铝合金有明显的温度敏感性,但是对应变速率的敏感性较弱.应变速率和温度对6013铝合金微观组织的影响显著,位错密度随应变速率的升高而增大,随温度的升高而减小.基于实验数据,求得了6013铝合金Johnson-Cook模型的本构参数并建立其本构模型.与实验结果进行对比,结果表明,所建立的本构模型能够很好地预测6013铝合金的流变应力.