Effect of Minor Alloy Additions on Aging Characteristics in Al-Zn-Mg Alloy Welds(Materials, Metallurgy & Weldability)
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An investigation has been made on the precipitation or solution behavior of the relatively insoluble compounds during solution treatment and the effect of minor alloy additions such as Cr, Mn, Ti, Fe-Si on the age hardening characteristics in commercial Al-Zn-Mg alloy by means of electrical resistivity measurement and transmission electron microscopy. The minor alloy added to the Al-Zn-Mg alloy forms relatively insoluble compounds during solution treatment. The considerable solution of the compounds takes place in the vicinity of weld bond region. The compounds affect the precipitation behavior at 120℃ aging, that is, the compounds delay the age hardening at 120℃ for the solution treatment at 380℃, but accelerate the age hardening for the solution treatment at 560℃. The addition of 0.05%Ti and 0.5%Mn hardly affects the age hardening characteristics. The addition of 0.25%Cr, 0.2%Fe-0.1%Si affects the age hardening. The age hardening is accelerated, as the solution of the compounds such as Al_<18>Cr_2Mg_3, Al_<12>Fe_3Si takes place. The age hardening is delayed, as the precipitation of the compounds takes place. The age hardening characteristics are affected by the difference of the precipitation sequence, because of the relatively insoluble compounds.
- Transactions of JWRI
Transactions of JWRI 14 (1), 69-76, 1985-07