高強度航太AA7000系(Al-Zn-Mg-Cu)合金:(I)熱加工、(II)淬火敏感性、與(III)抗應力蝕性之研究腐(第1年執行中，第2、3年新申請)

In 1936, Sumitomo Metal Ltd. had developed a thin plate called "extra superduralumin" which was resistant to stress corrosion cracking(SCC), and was laterused on a zero-type fighter aircraft. This is the first time 7000 series (AlZnMgCu)high-strength aluminum alloy (HS-7000) be practical application. Since then, inorder to meet the requirement of aerospace structure and components, 7000series alloys with higher specific strength, workability, weldability , and SCCresistance have been developed.However, three problems in the manufacturing and using of high strengthaerospace Al alloy of 7000 (HS-7000) series, namely (1) low hot working rate(<0.8mm/s), (2) Inability to perform on-line heat treatment; and (3) low resistant tostress corrosion cracking(SCC); The Al industry and academia are all hope toovercome these problems. In our pre-research found that the low hot workingrate was caused by the lower working temperature than (<450 °C). The alloys willbe partially melted at the grain boundary, if the working temperature is greaterthan 450 ° C, resulting in the fragility and the cracking.The reason for the inable to perform on-line solution treatment is due to the highquenching sensitivity of the alloy. When the alloy has high quenching sensitivity,the alloy will not form a supersaturated solid solution, resulting in a decrease inthe strength of the alloy. Therefore, this study attempts to apply the alloy designprinciples, with a variety of enhanced precipitation heat treatment (such as T6,T76, RRA, etc.), by theoretical to explore these two problems, anti-stresscorrosion and achieve development to meet the criteria aerospace materials(AMS) specification.As mentioned above, based on the process of the HS-7000 AlZnMgCu series(especially 7075) alloy, a three-year research plan is planned to investigate:(I)high hot working temperatures causing overheating of the HS-7000 seriesalloys, (II)Quenching sensitivity, and (III)low resistance to stress corrosion, canfully present the practical characteristics of this high-strength aluminum alloy. The3-year plan is:1st year: Effect of alloying and heat treatments on working temperature (ie:solution temperature) of wrought HS-7000 alloys (in progress)2nd year: Effect of alloying and heat treatments on quenching sensitivity ofwrought HS-7000 alloys (ie: resulting in inable to quench on-line) (newapplication)3rd year: Developed a wrought HS-7000 experimental alloy that can be deformedat high speed, on-line quenched, and SCC resistant. (new application) Based on the practical value and process troubles of the above- mentioned Thisstudy is expected to develop the wrought HS-7000 experimental alloy, which canbe used to establish its application information for Al academia and industry toprovide the valuable references