Al-Zn-Mg-Cu合金의 析出强化

다국어 초록 (Multilingual Abstract)

This paper aims to investigate the strengthening behavior by the age precipitation of Al-Zn-Mg-Cu alloy.
This could be achieved by the comparison and analysis of the strengthening behaviors of Al-Zn-Mg alloy, Al-Zn-Mg-Cu alloy and the alloy adding Cr and Mn to the latter alloy.
The close measurements of hardness, strength, electric resistivity were carried out after ageing and thermomechanical treatment at 90℃, 120℃ and 150℃.
The results obtained are summarized as follows.
1) The complex pre-precipitation zones of G. P. and G. P. B. increase the 0.2% proof stress much more compared with single pre-precipitation zone of G. P .. From this result, it is possible to deduce that complex zone makes a more effective contribution to strengthening than single zone.
2) The complex metastable phases of η´ and S´ increase the rate of strengthening of alloys more than the single η´ metastable phase does. Fromthis result, it is possible to deduce that the metas table phases of η´ and S´ have more effective strengthening than the metastable phase of η´.
3) The combined structure of the complex zones (G. P. + G. P. B.) and the complex intermediate phases (η´ + S´ ) makes a more effective contribution to strengthening than that of G. P. zones and η´.
4) The combined addition of Cr and Mn delays the formation rates of pre-precipitation zone and accelerates the rate of growth of metastable phase.
5) So it is resonable to find out that the hardness is decreased, but the strength is remarkably increased by the combined addition of Cr and Mn in AI-Zn-Mg-Cu alloy.