7075 Al 합금의 초소성 변형시 공동형성에 관한 연구

Cavitation during superplastic flow was investigated for 7075 Al alloy strained under uni-axial tension at 516℃. The 7075 Al alloy was thermomechanically processed to develop fine grain sizes of Bum and 12㎛, respectively. Cavitation and superplastic elongations between specimens with 8㎛ and 12㎛ were observed to be different. In the 8㎛ microstructure, the cavity stringers were formed along the tensile direction, whereas in the 12㎛ microstructure, the stringers were always oriented along the rolling direction, regardless of the tensile direction. The difference in the formation of cavity stringers seems to be mainly due to the distribution of the second phase particles in the matrix.