Fabrication and mechanical properties of ultrafine structured dissimilar laminated metal composite sheets (LMCS)

Abstract

The ultrafine grain structure is very difficult to fabricate by severe plastic deformation (SPD) for metals with poor formability. In this paper, a fabrication technology of ultrafine structured dissimilar laminated metal composite sheets (LMCS) was developed for poor plastic metals which have low elongation by hot accumulative roll bonding (ARB) in conjunction with cold rolling. The hot ARBed 1100/7075 LMCS was cold rolled at room temperature after recrystallization annealing treatment. An ultrafine structured dissimilar LMCS was obtained without undergoing severe cold rolled deformation. The mechanical properties were enhanced and optimized by using heat treatment technology. The accelerated refining mechanism of grain was revealed by microstructure characterization of the composite sheet. The enhanced strength was mainly derived from the fine layers, refined grains, increased dislocation accumulation, and abundant dispersoids. The results of the research are helpful in improving the mechanical properties of dissimilar LMCS and optimizing the preparation technology.

Interface Shear Actions and Mechanical Properties of Nanostructured Dissimilar Al Alloy Laminated Metal Composites

“…The instable interface curvature and individual layer shape lead to instabilities of the mechanical properties of LMCs. Previous studies show that the local accumulation of nonuniform strain causes the instability of mechanical properties, which can be proved by the results reported in the literatures [14,36,42,48,49]. The waviness of the bonding interfaces changes the total thickness of AA7075 layers along different sections of the LMCs sheets.…”

“…Previous studies show that the strength of dissimilar LMCs fabricated by ARB first decreases and then increases; the elongation decreases after two rolling cycles [37][38][39][40][41][42]. The increase of strength is contributed by the hardening of sample caused by piling up of the dislocations and grain refinement [20,23,48,49].…”

“…With the increase of strain, constituent metals begin to incur the nonuniform deformations, and the thickness of layers starts to vary. Necking starts to occur in the hard layer, and the soft layer protrudes into the hard layer filling it up [23,42,48,49]. The necking of the AA7075 layers causes its upper and lower surfaces to form an angle of about 30 ∘ , and the waviness of the AA1100 layers results in an angle between the bonding interfaces and the rolling direction of ±15 ∘ (Figure 4(b)).…”