The isothermal compression test for Ti-6Al-7Nb alloy was conducted by using Gleeble-3800 thermal simulator.The hot deformation behavior of Ti-6Al-7Nb alloy was investigated in the deformation temperature ranges of 940...The isothermal compression test for Ti-6Al-7Nb alloy was conducted by using Gleeble-3800 thermal simulator.The hot deformation behavior of Ti-6Al-7Nb alloy was investigated in the deformation temperature ranges of 940-1030℃and the strain rate ranges of 0.001-10 s^(-1).Meanwhile,the activation energy of thermal deformation was computed.The results show that the flow stress of Ti-6Al-7Nb alloy increases with increasing the strain rate and decreasing the deformation temperature.The activation energy of thermal deformation for Ti-6Al-7Nb alloy is much greater than that for self-diffusion ofα-Ti andβ-Ti.Considering the influence of strain on flow stress,the strain-compensated Arrhenius constitutive model of Ti-6Al-7Nb alloy was established.The error analysis shows that the model has higher accuracy,and the correlation coefficient r and average absolute relative error are 0.9879 and 4.11%,respectively.The processing map(PM)of Ti-6Al-7Nb alloy was constructed by the dynamic materials model and Prasad instability criterion.According to PM and microstructural observation,it is found that the main form of instability zone is local flow,and the deformation mechanisms of the stable zone are mainly superplasticity and dynamic recrystallization.The optimal processing parameters of Ti-6Al-7Nb alloy are determined as follows:960-995℃/0.01-0.18 s^(-1)and 1000-1030℃/0.001-0.01 s^(-1).展开更多
The hot deformation behavior of Ti 5.6Al-4.8Sn-2.0Zr-1.0Mo 0.35Si 0.85Nd alloy in β/quasi-β forging process was studied using isothermal compression tests over temperature range from 1040℃ to 1 100 ℃ and strain ra...The hot deformation behavior of Ti 5.6Al-4.8Sn-2.0Zr-1.0Mo 0.35Si 0.85Nd alloy in β/quasi-β forging process was studied using isothermal compression tests over temperature range from 1040℃ to 1 100 ℃ and strain rates form 0. 001 s-1 to 70 s -1. The results show that the flow stress and mierostrueture are sensitive to thermomechanical parameters. The processing maps based on the dynamic materials model at strain of 0.3 and 0.7 were established. The optimum deformation thermomechanical parameters at a strain of 0.7 have two regions that exhibit the peak of power dissipation efficiency. One is the region of 1062-1100 ℃ and 10- 3 10-1.5 s -1 ; and another which represents dynamic recrystallization is 1040-1045 ℃ and 10-1.8 10- 0.5 s -1. The instable region is located where the strain rate is larger than 1 s 1 which corresponds to the mechanical instability.展开更多
基金the National Natural Science Foundation of China(Grant No.51464035).
文摘The isothermal compression test for Ti-6Al-7Nb alloy was conducted by using Gleeble-3800 thermal simulator.The hot deformation behavior of Ti-6Al-7Nb alloy was investigated in the deformation temperature ranges of 940-1030℃and the strain rate ranges of 0.001-10 s^(-1).Meanwhile,the activation energy of thermal deformation was computed.The results show that the flow stress of Ti-6Al-7Nb alloy increases with increasing the strain rate and decreasing the deformation temperature.The activation energy of thermal deformation for Ti-6Al-7Nb alloy is much greater than that for self-diffusion ofα-Ti andβ-Ti.Considering the influence of strain on flow stress,the strain-compensated Arrhenius constitutive model of Ti-6Al-7Nb alloy was established.The error analysis shows that the model has higher accuracy,and the correlation coefficient r and average absolute relative error are 0.9879 and 4.11%,respectively.The processing map(PM)of Ti-6Al-7Nb alloy was constructed by the dynamic materials model and Prasad instability criterion.According to PM and microstructural observation,it is found that the main form of instability zone is local flow,and the deformation mechanisms of the stable zone are mainly superplasticity and dynamic recrystallization.The optimal processing parameters of Ti-6Al-7Nb alloy are determined as follows:960-995℃/0.01-0.18 s^(-1)and 1000-1030℃/0.001-0.01 s^(-1).
基金Item Sponsored by National Natural Science Foundation of China(51164030,51261020)Education Commission Foundation of Jiangxi Province of China(GJJ13501)
文摘The hot deformation behavior of Ti 5.6Al-4.8Sn-2.0Zr-1.0Mo 0.35Si 0.85Nd alloy in β/quasi-β forging process was studied using isothermal compression tests over temperature range from 1040℃ to 1 100 ℃ and strain rates form 0. 001 s-1 to 70 s -1. The results show that the flow stress and mierostrueture are sensitive to thermomechanical parameters. The processing maps based on the dynamic materials model at strain of 0.3 and 0.7 were established. The optimum deformation thermomechanical parameters at a strain of 0.7 have two regions that exhibit the peak of power dissipation efficiency. One is the region of 1062-1100 ℃ and 10- 3 10-1.5 s -1 ; and another which represents dynamic recrystallization is 1040-1045 ℃ and 10-1.8 10- 0.5 s -1. The instable region is located where the strain rate is larger than 1 s 1 which corresponds to the mechanical instability.
