ABSTRACT

Ti–6Al–4V fine-grained plates were manufactured using a rolling method and then subjected to superplastic tensile tests at varying temperatures and strain rates on an AG 250KNE electronic tensile testing machine. The superplastic behaviours of the plates were also tested. A cavity-growth model was established and the changing laws of energy during cavity growth and microstructure evolution of superplastic deformation were predicted. The Ti–6Al–4V alloy possessed the maximum elongation rate of 886% at 840°C and a strain rate of 5 × 10⁻⁴ s⁻¹. The strain-rate sensitivity index m for this alloy was 0.54. The mechanism of superplastic deformation was established to be strain-induced grain-boundary slip, and the mechanism of cavity growth to be plasticity-controlled cavity coalescence and growth.

摘要

Ti-6Al-4V 细晶粒板采用轧制方法制造，然后在 AG 250KNE 电子拉伸试验机上进行不同温度和应变速率的超塑性拉伸试验。还测试了板的超塑性行为。建立了型腔生长模型，预测了型腔生长过程中能量的变化规律和超塑性变形的显微组织演化。Ti-6Al-4V 合金在 840°C 时的最大延伸率为 886%，应变率为 5 × 10 ^-4 s ^-1。应变率敏感性指数m这种合金是 0.54。建立了超塑性变形机制为应变诱导晶界滑移，空腔生长机制为塑性控制的空腔聚结和长大。