TC4钛合金高温变形时的微观组织演变

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

摘要:

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1203 K时，初生α相晶粒尺寸逐渐减小，而低于1203 K时，初生α相晶粒尺寸呈波浪状变化。当变形温度高于1223 K时，初生α相体积分数呈波浪状变化，而低于1223 K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

Abstract:

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