TC4钛合金高温变形时的微观组织演变(英文)

Microstructure Evolution during High Temperature Deformation of Ti-6Al-4V Alloy

基于TC4钛合金压缩变形时的微观组织观察和定量金相实验,研究了变形工艺参数(变形温度、应变速率和变形程度)对微观组织演变和组织参数(初生α相晶粒尺寸和体积分数)的影响。结果表明:在α+β两相区,随着变形温度的升高,初生α相晶粒尺寸呈波浪状变化,初生α相逐渐减少;随着应变速率的增加,初生α相形貌由等轴状转变为长条状,微观组织参数的变化规律与温度有关,当变形温度高于1203K时,初生α相晶粒尺寸逐渐减小,而低于1203K时,初生α相晶粒尺寸呈波浪状变化。当变形温度高于1223K时,初生α相体积分数呈波浪状变化,而低于1223K时,初生α相体积分数逐渐减小;随着变形程度的增加,二次α相逐渐减少,初生α相晶粒尺寸呈先减小后略有增大的趋势,而初生α相体积分数变化较小。

The effect of processing parameters,including deformation temperature,strain rate and deformation degree on the microstructure evolution and the microstructure variables（grain size and volume fraction of primary α phase） was investigated based on the microstructure observation and the quantitative metallography of the isothermally compressed Ti-6Al-4V alloy.The results show that the curves of grain size of primary α phase are oscillatory in the α＋β two-phase region with increasing of the deformation temperature,and meanwhile the volume fraction of primary α phase decreases.The effect of the strain rate on the morphology of primary α phase is significant,while its effect on the microstructure variables of isothermally compressed Ti-6Al-4V alloy is dependent on deformation temperature.The grain size of primary α phase decreases with increasing of strain rate above 1203 K,but below 1203 K it fluctuates.The curves of volume fraction of primary α phase are oscillatory with increasing of strain rate above 1223 K,but below 1223 K the volume fraction decreases.The grain size of primary α phase increases slightly after a drop with increasing of the deformation degree,and meanwhile the secondary α phase decreases gradually.The effect of deformation degree on the volume fraction of primary α phase is not significant.