【摘要】 在840,870,900和930℃条件下分别对等轴Ti-6AL-4V合金进行总变形量为78%的热轧,随后对热轧Ti-6AL-4V合金的显微组织形貌、织构及动态力学性能进行研究。结果表明,当热轧温度达到900℃以上时,TI-6AL-4V合金中才发生再结晶及相变,显微组织类型由等轴组织变为双态组织,组织及再结晶等轴α晶粒的含量随热轧温度升高而增加。热轧Ti-6AL-4V合金中的织构随热轧温度变化而改变,但α晶粒的<0001>方向始终平行于轧板的法向。热轧Ti-6AL-4V合金的动态力学性能具有明显的各向异性,且各向异性规律随热轧温度的变化而改变。随着热轧温度的升高,沿法向加载时,合金的动态流变应力不断减小,绝热剪切临界失效应变不断增大;沿轧向加载时,合金的动态流变应力基本保持不变,但临界失效应变明显降低;沿横向加载时,合金的动态力学性能在840℃到900℃的热轧温度范围内基本保持不变,但当热轧温度为930℃时,合金的动态流变应力明显升高,临界失效应变明显降低。更多还原

【Abstract】 The equiaxed Ti-6Al-4V alloys were rolled with an overall reduction ratio of 0.78 at 840,870,900 and 930℃.The microstructure,texture and anisotropy of dynamic mechanical properties of the rolled alloy were investigated.Results show that the recrystallization and phase transformation do not occur until the rolling is performed at a temperature higher than 900℃,and then the microstructure of the rolled alloy turns into bimodal,while the amount of lamellarstructure and recrystallizedαgrains shows an increasing tendency with the increased rolling temperature.Moreover,it is interesting to find that although the texture varies with the rolling temperature,the<0001>direction ofαphase keeps parallel to the normal direction(ND)during the hot-rolling process at various temperatures.Based on the analyses of dynamic mechanical properties,Ti-6Al-4V alloy exhibits anisotropy of dynamic mechanical properties after hot-rolling at different temperatures.However,resulting from the rolling-temperature-depended texture and distribution of dislocation,the anisotropic tendency of dynamic mechanical properties varies with the rolling temperature.Moreover,with the increased rolling temperature,the dynamic flow stress loaded along ND decreases,while the adiabatic shearing failure strain slightly increases.The dynamic flow stress loaded along RD remains constant,while the adiabatic shearing failure strain exhibits an obviously decreasing tendency with the increased rolling temperature.The dynamic mechanical properties loaded along Transverse Direction(TD)remain constant when the rolling temperature is in the range of 840℃ to 900℃,while the dynamic flow stress loaded along TD increases evidently when the rolling temperature reaches 930℃,but the adiabatic shearing failure strain decreases greatly.更多还原