TA12A高温钛合金超塑性工艺参数实验研究

Experimental research on super-plastic parameters of high temperature titanium alloy TA12A

为了研究TA12A高温钛合金的超塑性工艺参数,利用2 mm厚板材进行了不同温度和不同初始应变速率下的高温拉伸试验,并观察了920℃拉伸试样的显微组织。结果表明,TA12A板材在900~940℃范围内以不同初始速率拉伸的伸长率均超过400%,具有良好的超塑拉伸性能。在温度为940℃和初始应变速率为1×10^(-3)s^(-1)时,断后伸长率最大可达785%;考虑在实际生产过程中温度越高则高温驻留时间越长,对成形后的材料性能降低越明显,最终确定超塑成形的工艺参数为:温度920℃,初始应变速率1×10^(-3)s^(-1);在超塑变形过程中,拉伸段的晶粒尺寸变大是保温时间和应变诱导的共同作用结果。

In order to study the super-plastic parameters of high temperature titanium alloy TA12 A,the high temperature tensile tests with2 mm thick plates were carried out under different temperatures and initial strain rates,the microstructure of specimen was studied at 920℃. The results show that the total elongation rates of TA12 A sheet are all above 400% at 900- 940 ℃ and good super-plastic tensile properties are obtaind. Elongation rate of 785% is obtained at 940 ℃ under the initial strain rate of 1 × 10^- 3s^-1. Considering that the higher temperature leads to longer keeping time and more obvious reduction of the material properties after forming in actual production process,the final process parameters are determined as temperature 920 ℃ and initial strain rate 1 × 10^-3s^-1. The grain size growth of stretch part is affected by both holding time and stain during super-plastic deformation.