论文部分内容阅读
采用分步超塑成形法研究了未经特殊细化的TC4-DT钛合金的超塑性。结果表明,在温度为860~950℃,应变速率为3.3×10~(-4)～1.0×10~(-2) s~(-1),预应变量为20%～80%,间隙保温时间为5～30min条件下,TC4-DT合金均表现出良好的超塑性(305.93%～506.67%)。变形温度为890℃,预应变量为50%,间隙保温时间为10min,第1步和第2步应变速率均为3.3×10-4 s~(-1)时,TC4-DT合金表现出最佳超塑性,伸长率为506.67%。真应力-真应变曲线表明,第2步开始时的应力明显小于第1步结束时的应力,第1步变形对该合金产生一定的软化作用。TC4-DT显微组织显示,动态再结晶一直伴随着整个分步超塑性变形过程,静态再结晶发生在间隙保温时间。再结晶行为的发生,为塑性变形提供了细小等轴组织,有利于该合金超塑性的提高。
The superplasticity of TC4-DT titanium alloy without special refinement was studied by the step-by-step superplastic forming method. The results show that the strain rate is 3.3 × 10 -4 to 1.0 × 10 -2 s -1 at the temperature of 860-950 ℃ and the prestrain is 20-80% TC4-DT alloy shows good superplasticity (305.93% ~ 506.67%) under the condition of 5 ~ 30min. TC4-DT alloy shows the highest deformation temperature of 890 ℃, pre-strain of 50%, gap holding time of 10min, and the first and second strain rates of 3.3 × 10-4 s ~ (-1) Good superplasticity, elongation of 506.67%. The true stress-true strain curve shows that the stress at the beginning of the second step is obviously less than the stress at the end of the first step, and the deformation of the first step produces some softening effect on the alloy. TC4-DT microstructure shows that dynamic recrystallization has been accompanied by the entire step-by-step superplastic deformation process, static recrystallization took place in the gap holding time. The occurrence of recrystallization behavior provides a small equiaxed structure for plastic deformation, which is favorable for the improvement of the superplasticity of the alloy.