Quench sensitivity of a 7003 aluminum alloy

The quench sensitivity of a 7003 aluminum alloy was determined by the time-temperature-transformation (TTT) curves and time-temperature-property (TTP) curves by an interrupted quench technique with measurement of as-quenched electro-conductivity and as-aged hardness. The microstructure transformation during isothermal treatment was studied by the transmission electron microscopy (TEM) and Avrami equation. The results show that the electro-conductivity of the 7003 alloy increases and the hardness decreases with prolonging the holding time at a certain isothermal temperature. The TEM observation indicates that the size and spacing of precipitates in the grain increase while those of grain boundary precipitates decrease and the precipitation free zones (PFZ) become wider with the prolongation of holding time at the nose temperature. The nose temperatures of the TTT and TTP curves are about 280and the incubation period is about 10 s. The CCT curves indicate that the cooling rate should be more than 4/s in the quench sensitive areas in order to get optimal mechanical properties. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.