变形工艺对TC11钛合金超塑性的影响

为了研究TC11(Ti-6.5Al-3.5Mo-1.5Zr-0.3Si)钛合金的超塑性变形行为,采用两种改锻工艺细化坯料原始组织,然后在电子拉伸试验机上分别以恒速、恒应变速率和最大m值法进行拉伸实验.结果表明,TC11钛合金在α+β区通过三维镦拔改锻工艺,可以获得晶粒度为6μm的细晶等轴组织,而在β区拔长改锻的组织为粗大的魏氏组织.在变形温度为900℃的条件下,TC11钛合金通过最大m值超塑变形方式获得了异常高的超塑性,最大伸长率达到2300%;而采用常规的恒应变速率和恒速超塑变形,伸长率分别为1147%和1100%.说明TC11钛合金在α+β区通过三维镦拔改锻细化晶粒后,以最大m值超塑变形是获得较好超塑性的有效方法.

Effect of deformation process on superplasticity of TC11 titanium alloy

In order to investigate superplastic deformation behavior of TC11 titanium alloy, two forging processes were carried out to refine the original microstructure of the alloy, and then tensile tests were conducted on an electronic tensile tester by using maximum m value superplastic deformation(MaxmSPD) method and the conventional methods of the constant strain-rate and constant velocity superplastic deformation. The results show that a fine equiaxed microstructure of TC11 titanium alloy with grain size of about 6μm is obtained through three-dimensional upsetting and stretching in α+β region, however, a coarse Widmanstatten structure is observed in the alloy stretched in β region. At the deformation temperature of 900℃ , TC11 titanium alloy exhibits exceptionally high superplasticity with maximum m value superplastic deformation, and the greatest elongation reaches 2300% . However, with the conventional methods of the constant strain-rate and constant velocity superplastic deformation, the greatest elongation of TC11 alloy is 1147% and 1100% , respectively. It is suggested that MaxmSPD is an effective methed for obtaining the good superplasticity through three-dimensional upsetting and stretching to refine microstructure in α+β region of TC11 titanium alloy.