8090A1-Li 합금의 공동화에 미치는 응력상태 및 정수압의 영향

It has been shown that the application of hydrostatic pressure during superplastic forming of 8090A1 can prevent the cavitaiton normally encountered at atmospheric pressure and cavity growth rate factor .eta. in the plane strain state is greater than that in the equibiaxial stress state. .eta. value shows some difference compared to the theoretical value, which seems to be due to the continuous nucletion and coalescence of voids during superplastic deformation. Scatter of measured data of cavity volume fraction seems to be on preferential nucleation of viods on non-uniformly distributed second phase particles in the deforming matrix.