TB8钛合金形变诱导超塑性研究

Study on strain-induced superplasticity of TB8 titanium alloy

采用形变诱导法对TB8钛合金进行了超塑性拉伸实验,研究了变形温度、预变形量和中间保温时间对该合金超塑性性能及微观组织演变的影响。结果表明:与恒应变速率法拉伸相比,该方法拉伸后合金的超塑性得到大幅度地提升;变形温度为750℃、预变形量为50%和保温时间为20 min时,该合金的超塑性能最好,伸长率为796.1%。预变形阶段,脱溶析出和再结晶双重优化作用使亚稳态β相转变为细小均匀的再结晶组织,在后续变形过程中,细小弥散的α相既能抑制再结晶晶粒过分长大,又能在一定程度上使再结晶组织发生应变集中而破碎。超塑性变形后合金的微观组织仍然保持较好的等轴状,具有典型的超塑性变形特征。

The superplastic tensile test of TB8 titanium alloy was carried out by means of strain inducing method,the effects of deformation temperature,pre-deformation and intermediate holding time on superplastic properties and microstructure evolution of the alloy were studied. The results show that the superplasticity of the alloy stretched by strain inducing method is greatly improved compared with that by the constant strain rate method; when the deformation temperature is 750 ℃,pre-deformation is 50% and holding time is 20 min,the superplastic properties of the alloy is the best,with elongation of 796. 1%. In the stage of pre-deformation,the metastable β phase transforms into small uniform recrystallization organization by the dual optimization with exsolution precipitat and recrystallization,in the subsequent deformation process,the small dispersion of α phase not only can inhibit the recrystallization of grain growth,but also make the recrystallization organization broken due to strain concentration to a certain extent. The microstructure of the alloy after superplastic deformation remains good equiaxed,with significant superplastic deformation characteristics.