Investigation of particles on the microstructure, texture and formability of Al-Mg-Si-Zn alloy for automotive body sheet

The effects of different size and number distributions of particles after intermediate annealing treatment on the final microstructure, texture and formability of Al-Mg-Si-Zn alloy after solution treatment were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometer (XRD) and tensile testing machine. The results indicated that there were significant differences in grain size and the texture intensity and volume fraction of the Cube(ND) {001} <310> texture of three alloy sheets (annealed at different heating and cooling rates) after solution treatment due to the effect of different particle sizes and number distribution on the nucleation and growth of recrystallized grains. As a result, the recrystallized grain nucleation and growth mechanisms of those three alloy sheets were established, and the relationship between microstructure, texture and formability was analyzed. In addition, the distribution of the size and number of particles formed by annealing treatment with rapid heating (heating rate of 70 degrees C/min) and air cooling was more favorable to the formation of finer recrystallized grains and weaker texture, so that the sheet obtained higher average plastic strain ratio (r) over bar values and lower anisotropic index Delta r values, which improved the formability.