Softening Behavior of a New Al-Zn-Mg-Cu Alloy Due to TIG Welding

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• 作者：Liang Zhang ; Xiaoyan Li ; Zuoren Nie…
• 刊名：Journal of Materials Engineering and Performance
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：25
• 期：5
• 页码：1870-1879
• 全文大小：2,615 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Characterization and Evaluation Materials
  Materials Science
  Tribology, Corrosion and Coatings
  Quality Control, Reliability, Safety and Risk
  Engineering Design
  
• 出版者：Springer New York
• ISSN：1544-1024
• 卷排序：25

文摘

A new Al-Zn-Mg-Cu alloy with T6 temper was welded by TIG welding, and the softening behavior of the joint was evaluated. Results show that the ultimate tensile strength of the joint is 436.2 ± 26.4 MPa which is about 64.5% of that of the base metal (BM). Fusion zone (FZ) is the weakest region even though its microhardness increases from 107.6 to 131.3 HV within 90 days after welding. Microhardness of the heat-affected zone (HAZ) adjacent to FZ increases from 125.2 to 162.3 HV within 90 days. However, a valley value of microhardness appears in the rest of the HAZ that increases from 112.1 to 128.1 HV within 90 days. The variation of grain size and precipitates is regarded as the main cause of softening in both FZ and HAZ. The grain size of FZ is about 33.9 μm, whereas 8.7 and 8.4 μm for HAZ and BM, respectively. A large number of η′ phases distribute dispersively in BM, whereas precipitates in FZ identified as GPI zones are finer and fewer. Besides, precipitates in HAZ adjacent to FZ are also GPI zones. Precipitates in HAZ far away from FZ are coarser and fewer than those in BM and η phases begin to emerge.Keywordsaluminumfusion zoneheat-affected zonesofteningwelding