Abstract
The cavitation behavior and forming limits of a high-strain-rate superplastic 21 vol.% SiC whisker-reinforced Al-4.4Cu-1.5Mg (Al-4.4Cu-1.5Mg/21SiCw) under biaxial stress states were investigated in this paper. The composite sheet was bulged using dies with aspect ratios of 1:1, 4:3 and 2:1 at the constant applied stress of 4 MPa and at the optimal temperature of 793 K determined from superplastic tensile tests. The thickness distributions of bulged diaphragms were measured at different strain levels. For diaphragms deformed equibiaxially, a good agreement between experimental thickness distributions and the theoretical predictions of Cornfield and Johnson (Int. J. Mech. Sci. 12 (1970) 479) was observed at fractional heights of the deformed diaphragms ranging from 0.4 to 1.0. The cavitation behavior of the composite under biaxial tension was compared with that of uniaxial tension. It was found that at a similar effective strain, the amount of cavities obtained under equibiaxial tension is slightly greater than that under uniaxial tension, and the cavity growth rate parameter under uniaxial tension was also slightly larger than that of uniaxial tension. The influence of stress state on cavity growth rate was discussed. Limit strains of Al-4.4Cu-1.5Mg/21SiCWat different stress ratios were predicted based on a plastic damage model recently developed for superplastic materials (Chan and Chow, Int. J. Mech. Sci., submitted). The trend of the prediction was in good agreement with the experimental findings.
Original language | English |
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Pages (from-to) | 49-57 |
Number of pages | 9 |
Journal | Materials Science and Engineering A |
Volume | 340 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 15 Jan 2003 |
Keywords
- Aluminum-based composite
- Cavitation
- Limit strains
- Superplasticity
ASJC Scopus subject areas
- General Materials Science