Effect of lamellar structural parameters on the bending fracture behavior of AA1100/AA7075 laminated metal composites

Abstract

• The Al/Al laminated composites with excellent interface state were fabricated by accumulative roll bonding. • Toughening mechanism of Al/Al laminated composites under the condition of various lamellar structure parameters was explored. • The change of thickness in soft layer was considered as a main reason for affecting bending properties. • Crack deflection and arresting contributed to the extra toughness enhancing in the laminated composite with higher layer number. The lamellar structure has an important impact on the mechanical properties of dissimilar laminated metal composites (LMCs), including the thickness ratio of dissimilar metal constituent layers and the number of layers. AA1100 and AA7075 with thickness ratios of 1:4 and 3:4 were fabricated for multilayer AA1100/AA7075 LMCs by hot accumulative roll bonding (ARB) technology. The bending fracture characteristics of AA1100/AA7075 LMCs with different thickness ratios and numbers of constituent layers were investigated. The research results indicated that AA1100/AA7075 LMCs with a low thickness ratio exhibited better bending ductility and toughness than those with a high thickness ratio, which was attributed to the crack growth resistance caused by the thickness of the soft AA1100 layer. The toughening mechanism introduced by crack deflection or arresting contributed to the enhancement in the toughness of the LMCs compared with that of the single 7075Al layer. The bonding interfaces of AA1100/AA7075 LMCs with different numbers of layers are continuous and straight due to the high ARB temperature. A decrease in bending toughness was observed as the number of layers increased. Unlike LMCs with a low number of layers, crack deflection or interface delamination is also considered a main toughening mechanism in dissimilar LMCs in addition to the thickness effect.