Ti-6Al-4V合金板の温間プレス成形法の開発と肉厚制御

抄録

In general, Ti-6Al-4V alloy sheets are formed by incremental press forming in the temperature range between 600 and 900 ℃. In this temperature range, the ductility of Ti-6Al-4V alloy is improved. Because of the low ductility of Ti-6Al-4V alloy at the temperatures between room temperature and 600 ℃, fracture easily occurs during press forming. Hence, a method of press forming of Ti-6Al-4V alloy sheets at 300 ℃ was developed. In this method, the punch motion and blank holding force were applied separately to prevent fracture at the punch radius until the maximum punch load was reached, and the deep drawing process was demonstrated from the maximum punch load until finish forming to prevent the fracture at end of the flange. In addition, by applying the developed method, we were able to prevent the decrease in wall thickness at the punch shoulder, compared with that in press forming. As a result, warm press forming of Ti-6Al-4V alloy sheets at 300 ℃ was achieved without fracture of the formed cup or local decrease in the wall thickness by applying the developed method.