Formation of Heterogeneous Microstructure in AA1050/AA5052/AA6061/AA1050 Layered Sheet Processed by Cold Roll-Bonding and Subsequent Annealing

Abstract

A cold roll-bonding process was applied to fabricate an AA1050/AA6061/AA5052/AA1050 four-layer clad sheet and subsequently annealed. Three types of aluminum alloy sheets such as AA1050, AA6061 and AA5052 with 2 mm thickness, 40 mm width and 300 mm length were stacked up each other after such surface treatment as degreasing and wire brushing, then reduced to a thickness of 2 mm by multi-pass cold rolling. The rolling was performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at rolling speed of 6.0 m/sec. The roll bonded AA1050/AA6061/AA5052/AA1050 clad sheet was then annealed for 0.5 h at 200~400 °C. Microstructures of the as-roll bonded and subsequently annealed aluminum sheets are investigated by electron back scatter diffraction (EBSD) measurement. After rolling, the roll-bonded AA1050/AA5052/AA6061/AA1050 sheet showed a typical deformation structure that the grains are largely elongated to the rolling direction. However, after annealing, it exhibits a very heterogeneous structure consisting of both deformation structure and recrystallization structure containing nanometer order grains. The formation of this heterogeneous structure and texture with annealing is investigated in detail through EBSD analysis.

Effect of micro-cracks on mechanical and damping properties of double-layered Al/Al plate

“…As a promising solid-phase welding technique, cold roll bonding (CRB) is established by the combined plastic deformation of metals to be joined [1]. This technology has been utilized to produce layered sheets and composite strips, including two-layered metal (such as Al/Al, steel/steel, Cu/Cu, Al/Cu, Al/Ti, Al/Mg, Al/Zn, Al/steel, Ti/Ni, Ag/Cu and Cu/Nb [1]), three and multilayered sandwich composite (such as Al/Al/Al [2][3][4], Al/Cu/Al [5], Cu/Cu/Cu [6], Ti-Ni/Ti-Ni/Ti-Ni [7], Al/Al/Al/Al [8] and Al/Al/Al/steel [9]), metal-matrix composite (such as Al with Ti particles [10], Al with Al 2 O 3 particles [11], Al with TiO 2 particles [12], steel with SiC [13] and Cu with carbon nanotubes [14]) and porous metal (such as aluminium foam [15]). Among these, porous metallic material possessing superior damping capacity and lightweight to fully dense one attracts the researchers' attention, and it is currently manufactured by adding TiH 2 on the bonding surface before CRB and heating the bonded sheet after CRB (shown in Figure 1(a,b)) [16].…”