成形极限用于评价板材成形性能,通常采用成形极限图表示。TNW700为新型高温钛合金材料,长时间工作温度为500℃,短时工作时间为700℃。采用钢模胀形的方法,对TNW700进行了750,800和850℃温度下高温成形极限试验研究。结果表明,平面应变路径下的800与850℃的极限主应变比750℃分别提高29.4%与44.5%,说明材料成形极限随温度升高而提高,微观断口呈现明显韧窝,表明TNW700为延性断裂;基于试验数据拟合了成形极限经验模型参数,在此参数下计算的极限曲线与试验数据符合较好。 Forming thresholds are used to evaluate sheet formability and are usually plotted as forming limits. TNW700 is a new high-temperature titanium alloy material, long working temperature is 500 ℃, short working time is 700 ℃. Using the method of bulging the steel die, TNW700 was subjected to the high temperature forming limit test at 750, 800 and 850 ℃. The results show that the ultimate principal strain at 800 and 850 ℃ increases by 29.4% and 44.5%, respectively, under the plane strain path, which shows that the material forming limit increases with the increase of temperature and the microscopic fracture shows obvious dimples, indicating that TNW700 is a ductile fracture Based on the experimental data, the forming limit empirical model parameters are fitted. The limit curves calculated by this parameter are in good agreement with the experimental data.