Effect of Aging Treatment Regime on Mechanical Properties and Precipitation Behavior of 7003 Aluminum Alloy Extruded Materials

This paper investigates the effect of a heat treatment regime on the precipitation behavior in industrially extruded 7003 aluminum alloys. The results show that the strength of 7003 aluminum alloy after natural aging after extrusion is relatively low; from peak aging to regression re-aging, the yield strength rises sharply to the maximum, and the elongation of regression re-aging specimens decreases to 5.8-23.8% compared with the first two. With the transition from natural aging to peak aging heat treatment process, the second phase in the grain gradually grows and its distribution and its dispersion, and the grain density gradually decreases. The GP zone and metastable phase Mg-Zn2 are the main precipitation phases during the heating process of the regression re-aging heat treatment, and at the cooling stage, the GP zone gradually disappears, and metastable phase Mg-Zn2 continuously refines with the formation of matrix precipitates, the grain density gradually increases, and the precipitation phase transformation becomes more compact after re-aging. After Al3Zr as the primary nucleation site at this point, more finely dispersed Mg-Zn2 particles subsequently appear, showing a large number of dislocations as well as discontinuously distributed grain boundary precipitate.