Shear Spinning of Nickelbased Super-Alloy 718

Abstract

Manufacturing of aerospace engine components by very high straining methods require knowledge of the material response to solution heat treatment . This paper presents evaluation of the shear-spinning forming process by experimenting, with different heat treatment temperatures and time at temperature , to increase knowledge of re-crystallisation of the strained grains. Spinning and shear-spinning has the potential to replace conventional sheet metal forming methods for small to medium volumes by reducing cost, increase flexibility, lower forming forces and reduced development time. The shear spinning performed resulted in an engineering strain of 176% in the axial direction and −55% in the sheet thickness direction. The hardness increased from HV_1.0 kg228 to HV_1.0 kg446. The heat treatment experiments showed that the lower end solution treatment is sufficient to reach full re-crystallisation in Alloy 718 even at a time as low as 20 min. Low to medium temperatures resulted in significant grain size reduction due to re-crystallisation. Using the higher end of the temperature range the original grain size and hardness could be re-established. Low solution temperature resulted in an increase of delta phase in the grain boundaries and inside the grains which was not found at the higher temperatures.