分步拉伸变形对TA15合金超塑性的影响

Effect of Multi-Step Tension on the Superplasticity of TA15 Alloy

采用分步变形法对TA15合金在10kN高温电子拉伸试验机上进行了超塑性拉伸试验，研究了变形温度和预变形量对该合金超塑性性能及微观组织演变。结果表明：变形温度为850～950℃和预变形量为100％～200％时，TA15合金呈现出良好的超塑性；变形温度为900℃和预变形量为150％时，该合金的超塑性能最好，最大延伸率为1456％；变形温度为950℃时，该合金的超塑性能降低，延伸率仅为188％。TA15合金的微观组织状态显示：该合金在拉伸变形过程中微观组织保持等轴状，但是随着变形温度的升高，晶粒开始长大，变形温度越高，晶粒长大越显著。

The superplastic tension of TA15 alloy was carried out through a multi-step tension method. The superplasticity and microstructure of TA15 alloy were investigated at different deformation temperatures and pre-tensile elongations. The results indicate that the TA15 alloy exhibits good superplasticity at all deformation temperatures from 850 to 950℃ and pre-tensile elongations from 100% to 200%. The best superplasticity can be obtained at a pre-tensile elongation of 150% and deformation temperature of 900 ℃, and the maximum elongation in the superplastic tension of TA15 alloy is 1456%. The superplastic elongation decreases to 188% at the deformation temperature of 950℃. The microstructure shows that the TA15 alloy is of equiaxed-shape after the tension, and this is a typical microstructure for superplastic deformation. But the grains grow up with increasing of deformation temperature. The higher the deformation temperature of TA15 alloy is, the more remarkably the grainsgrow.