高强度抗腐蚀易焊接Al-Mg合金以固溶强化和加工硬化为主要强化手段，是船板和装甲板轻量化的最佳选择之一。但Mg大于5-6%时，进一步增加Mg含量对合金抗腐蚀和热加工性能损害极大，使该系合金的发展受到极大的限制。AA5059合金中添加一定量的Zn可使合金的强度和耐蚀性获得显著提高，但对未来尖端的船舶、军车所需Al-Mg系合金来说仍然不足。本项目拟突破传统Al-Mg合金的成分设计思路，通过大幅度提高合金中的Zn含量，使加工硬化型Al-Mg合金具有析出强化能力，即在晶内形成大量含Zn相，从而在不损坏抗腐蚀性能的条件下，使新合金同时实现加工硬化、固溶强化和析出强化能力，显著提升合金的强度水平。课题将针对析出强化的控制及机理进行系统深入分析研究，同时研究新合金的抗晶间腐蚀机理。建立新型合金成分、加工处理、组织和性能间的关联模型，为研究开发具有自主知识产权的新型高性能船舶及装甲用铝合金材料奠定基础。

Among all the Al alloys, Al-Mg alloy has been one of the most suitable materials for vessels and military vehicles due to its reasonable mechanical properties, good corrosion resistance and good weldability. Generally, Al-Mg alloy is strengthened by solid solution strengthening and work hardening. When Mg content is higher than 5-6%, the corrosion resistant property and hot rolling capacity dramatically decrease with increasing Mg content, which greatly limited the development of the alloy. By the addition of a small amount of Zn, AA5059 achieves higher mechanical and corrosion resistant properties. But it is still not enough for the use on advanced vessels and military vehicles.In this proposal, we are able to transfer the traditional non-heat treatable Al-Mg alloy to precipitation hardened alloy by the addition of a large amount of Zn than AA5059. The Zn containing intermetallic compound will serve as the main precipitation strengthening phase inside the grain. By optimizing the ageing and precipitation process, the newly developed alloy will simultaneously possess work hardening, solid solution strengthening and precipitation hardening, and thus dramatically increase the strength of the alloy. At the same time, we are able to reduce the amount of Al-Mg intermetallic compound and prevent continuous precipitation on the grain boundary. Thus, improve the intergranular corrosion resistant property of the alloy. In this proposal, we systematically investigate the mechanism of precipitation hardening and the mechanism of intergranular corrosion during ageing treatment. The final goal is to establish the corresponding relationship between the properties, microstructure, chemical composition and ageing treatment of the newly developed Al-Mg alloy.