In general, Ti-6Al-4V alloy sheets are formed by press forming in the temperature range of 600 and 900 ℃, which improves ductility. Because of the low ductility of Ti-6Al-4V alloy at temperatures between room temperature and 600 ℃, fracture easily occurs during press forming. Hence, to achieve press forming at 300 ℃, a method of press forming of Ti-6Al-4V alloy sheets at warm forming was developed. In this method, the punch motion and blank holding force were applied separately and incrementally to prevent fracture at the punch radius. In addition, the effects of forming conditions such as lubrication condition and punch motion on warm incremental press forming were investigated to achieve warm press forming without lubrication. As a result, by controlling the punch motion and punch speed in warm incremental press forming, we were able to obtain a formed cup without lubrication, the same as by forming with lubrication. By comparing the results at 300 and 500 ℃, we clarified that the formability was not affected by the forming temperature in warm incremental press forming.
