细晶Ti-6Al-4V 宽幅板材的超塑性变形机理及组织演变

Superplastic deformation mechanism and simultaneous microstructure evolution of fine grained Ti-6Al-4V wide sheet

摘要:

通过恒应变速率拉伸试验，在1103K-1223K温度范围、3.2×10-4 s-1 to 1×10-2s-1应变速率范围内，研究了Ti-6Al-4V宽幅板材的超塑性，在实验中获得了100%-604%延伸率。分析了组织演变和变形机理，其主要变形机理为晶界滑移，以晶内位错运动和β相的晶内滑移为协调机制。实验中还发现在低温下变形时，Ti-6Al-4V宽幅板材存在各向异性，当在高温下变形时，各向异性不太明显。

Abstract:

The superplasticity of fine grained Ti-6Al-4V wide sheet was investigated by constant strain rate tensile method in this work. The superplastic tensile tests were carried out at temperatures ranging from 1103K to 1223K and strain rates from 3.2×10-4 s-1 to 1×10-2s-1. The tensile elongation to failure values between 100% and 604% were obtained. Microstructure evolution and deformation mechanism were analyzed. The main deformation mechanism was grain boundary sliding, accommodated by matrix dislocation movement and the intragranular slip of β phase. It was also found that the Ti-6Al-4V wide sheet showed anisotropy when deformed at lower temperatures, which was obviously reduced when deformed at higher temperatures.