抄録
The strengthening of Al-Zn-Mg-Cu system alloy results from the interaction between dislocation and solute atoms or precipitates. In this study, the tensile properties of 7475 aluminum alloys having various average grain sizes were evaluated. The 0.2% proof stress and elongation were discussed based on the theory of dislocation mechanism and the observation of microstructures. The main results obtained were as follows:
(1) The 0.2% proof stress, tensile strength and elongation of the materials increased with decreasing average grain size.
(2) In accordance with the Hall-Petch's relation, the 0.2% proof stress was plotted against the reciprocal square root of the average grain size of the aluminum matrix. A good correlation was obtained, indicating that the 0.2% proof stress depends on the average grain size of the aluminum matrix.
(3) The contributions of the precipitation strengthening, solid strengthening and grain refining effect to the 0.2% proof stress of the present 7475 aluminum alloy were estimated to be 258, 153 and 5MPa, respectively.
