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本文通过研究具有不同微观结构的Ti-6Al-4V合金板材在不同变形速率及不同温度下的变形行为,对变形速率敏感指数m的物理意义及出现超塑性的最低温度作了探讨。总结出在超塑性变形过程中,流变应力σ与温度T及变形速率ε之间的关系式: σ=cε~me~(U/RT) 以此方程为基础,确定出的m值与温度无关,仅取决于材料的微观组织结构。并提出了超塑性转变温度S_t的新概念。若采用这两点以表征材料的“超塑性”性质,则可使问题变得简单。
In this paper, the physical meaning of the sensitivity index m of the deformation rate and the minimum temperature at which superplasticity occurs are discussed by studying the deformation behavior of Ti-6Al-4V alloy plates with different microstructures at different deformation rates and different temperatures. The relationship between flow stress σ and temperature T and deformation rate ε is summarized in the process of superplastic deformation: σ = cε ~ me ~ (U / RT) Based on this equation, the relationship between m and temperature Independent, depends only on the microstructure of the material. A new concept of superplastic transition temperature S_t is proposed. Using these two points to characterize the material’s “superplasticity” makes the problem easier.