Effects of microstructure on bendability of Al-Mg-Si alloys

摘要

To reduce the weight of vehicle body structures, Al-Mg-Si alloys which benefit from artificial aging during paint bake cycle have been used in outer panels of automobiles. One of important requirements in these alloys is their ability to resist fracture in hemming. In this paper, the effect of Si and Fe contents on the bendability of Al-Mg-Si alloys has been investigated. The bendability is declined with increasing Si and Fe contents in these alloys. It is obvious that bendability is related to size distribution of second phase particles. Small cracks on the surface of a specimen seem to appear in the interface between second phase particles and matrix during bending test and many particles can be observed near an initial crack line across several grains on the surface. Intragranular crack formation and propagation play an important role in the mechanism of bend crack occurrence.