Ti3Al基合金板材的超塑性研究

研究非典型等轴细晶的两种不同轧制变形量的Ti3Al基合金热轧板的超塑性变形行为及其变形前后的显微组织。研究结果表明:该合金在超塑性变形过程中组织会转化为有利于超塑性的细小等轴组织。其在变形温度为940～1020℃,应变速率为2×10-4～2×10-3S-1时具有良好的超塑性,其最大伸长率可达859.5%,应变速率敏感指数达0.43,该合金超塑性变形的主要机制是晶界滑动,而且这种非典型等轴细晶条件下超塑性变形时晶内变形以及位错蠕变所起的作用比在等轴细晶态组织条件下的作用更为显著。对非典型等轴细晶的Ti3Al基合金热轧板,无需进行复杂热处理,也可以获得良好的超塑性,更具有工业意义。

Investigation on Superplasticity of Ti3Al Alloy Sheet

Superplastic deformation behavior and microstructure evolution of two hot-rolled Ti3Al base alloy sheets with different strain and atypical equiaxed grains were studied in this paper.The results show that,microstructure of the alloy transformed from the initial non-equiaxed microstructure to fine equiaxed microstructure,which is regarded as beneficial for superplastic deformation.The alloy exhibited good superplasticity when deformed at the temperature range of 940~1020℃,with the strain rate of 2×10-4 ~2×10-3s-1,the maximum elongation can be reached 859.5% and the strain rate sensitivity index is high at 0.43.The superplastic deformation mechanism of this alloy is mainly for boundary sliding.The effects of deformation inside the grains and dislocation creep during the superplastic deformation are more significant in this atypical equiaxed microstructure condition than those in the typical fine-equiaxed conditions.Hot-rolled Ti3Al base alloy sheets with atypical equiaxed grains have excellent superplasticity and do not need complex heat treatments,which represents good commercial value.