Effect of Sr on forming properties of Al-Mg-Si based alloy sheets
(1.School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China
2.河南省郑州市郑州工业大学材料科学与工程系)
2.河南省郑州市郑州工业大学材料科学与工程系)
Abstract: The effects of Sr element on the forming properties of the Al-Mg-Si based alloy sheets were studied by tensile test, metallograph, DSC, XRD, SEM and TEM. The results show that the tensile strength of aluminum alloy sheet added 0.033%(mass fraction)Sr increases comparing with that of free Sr. Simultaneously, the forming properties of sheets evidently increase, the elongation hardenability (n) and plastic strain ratio (r) and Erichsen number increase 27.8%, 11.1%, 10.8% and 12%, respectively, and the forming limit diagram increases evidently, too. The analysis shows that Sr is surface active element, which can refine grains of alloys, promote precipitation, reduce activation energy of β″ phase, and lead the formation of a-(Al8Fe2Si) phase instead of β-(Al5FeSi) phase. As a result, the forming properties of the alloy sheet increase.
Key words: microelement Sr; Al-Mg-Si based alloy sheets; forming properties