The Effects of Different Artificial Aging Treatments on the Tensile Properties of Friction Stir Processed Al-xZn-1Mg Aluminum Alloys

• Main Authors: Wen-TingChiang, 姜文挺
• Other Authors: Truan-Sheng Lui
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/01102454710458838162

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 98 === The precipitation-hardening 7xxx series aluminum alloys are widely used in the aircraft and military industry, due to the higher strength and fracture toughness than other series aluminum alloys. Now the most researches about friction stir process focus more on high Mg content 7050 and 7075 alloy, which showed the tensile properties would be worse than the base metal (T6 treatment), but less on low Mg content alloys. In this study, we are aimed to observe the change of tensile properties by several artificial aging treatments on friction stir processed low Mg content commercial 7005 Al alloy, which is also called ZM35 because of its Zn/Mg ratio. In order to compare with ZM35, we also use the same process on ZM57 alloy which has different Zn/Mg ratio. After the process of friction stir and then natural aging for 12 days, the experiment results show that the strength of ZM35 and ZM57 would be deteriorated compared to base metal. The deterioration rate of YS is more than 30% and UTS is about 10%, but the ductility is raised to 20% instead. Thus, after the several artificial aging treatments, the strength of the material which is as-FSP condition could be promoted, but it still worse than base metal. In the several artificial aging treatments, one-step (40℃/96hr and 80℃/16hr) and two-step (80℃/16hr+T6) treatments exhibit the similar results for ZM35 and ZM57 alloys. In addition, the strength of the material which is as-FSP condition could be improved by using two-step treatments. After three-step (T4+80℃/16hr+T6) treatment, the tensile properties have different results in ZM35 and ZM57 alloys: for ZM35, the strength became better and the ductility got worse than two-step treatments; for ZM57, the strength and the ductility both decreased, and the deterioration rate of the ductility even reached 60%.