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

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.

Manufacturing of three-layered sandwich composite of AA1050/LZ91/AA1050 using cold roll bonding process

In this paper, for the first time, dual-phase Mg-Li alloy is used to produce a three-layered Al/Mg/Al composite with the use of the cold roll bonding process. The low density and high ductility are known as the essential advantages of the Mg-Li alloys, while a couple of important problems should be taken into account, namely low corrosion resistance and low strength. It has been tried to deal with the mentioned problems by performing cold work and cover the Mg sheet with the Al similar plates. To investigate the Mg-Al layers bonding quality, mechanical properties and microstructure were examined for different thicknesses reduction ratio. The peeling test results showed that with increasing rolling pressure, the size and number of cracks on the brittle surfaces due to brushing, surface expansion, and metal extrusion between the cracks were improved by rising the reduction thickness ratio, bond strength enhanced, sharply. The UTS of 33.33% thickness reduction three-layered Al/Mg sample was obtained 186.5 MPa, which was more than 2.1 and 1.3 times higher than the initial Al1050 and MgLZ91 samples, respectively. However, because of increasing the amount of thickness reduction, roll-bonded layers’ quality, the tensile strength of the composite, and the microhardness of both layers increased. Furthermore, the elongation has reduced, and the maximum ultimate tensile strength and microhardness were achieved at 66.67% thickness reduction.

Mechanical bonding in cold roll-cladding of tri-layered brass/steel/brass composite

In this paper, brass/steel/brass clad-composite was fabricated using a cold roll-bonding process. Composite sheets were roll-bonded at reduction ratios between 37 and 72% at room temperature from strips of 150 mm in length and 30 mm wide, in one pass without lubrication. The threshold deformation for successful bonding was at a thickness reduction of 48% and peel strengths of the bonds were measured to be approximately 12 N cm-1, and it was found to escalate with an increase in the rolling reduction. The optimum reduction in thickness was ~66% wherein the peel strength was ~33 N cm-1. Various techniques such as optical and electron microscopy were implemented to analyze and investigate the effects of the reduction in thickness and the joining mechanism. The results showed that an increased reduction in thickness in rolling leads to an increase in the joining strength. Furthermore, increasing the brass plate thickness negatively affects the joining strength. A Cu peak on the peeled-off steel surface and the presence of Fe on the peeled-off brass surface strongly suggest that the major bonding between brass and steel was mechanically induced metallurgical bonding.

Effect of Annealing on the Interface and Mechanical Properties of Cu-Al-Cu Laminated Composite Prepared with Cold Rolling

Cu-Al-Cu laminated composite was prepared with cold roll bonding process and annealing was carried out to study the phase evolution during the annealing process and its effect on the mechanical properties of the composite. The experimental results showed that after annealing the brittle intermetallics in the interface mainly includes Al4Cu9, AlCu and Al2Cu. With the increase of annealing temperature, the tensile strength of the composite decreases and the elongation shows a different variation which increases at the beginning and then decreases after a critical point. This phenomenon is related to the evolution of intermetallic compounds in the interface of the composite. It was also found that the crack source of the tensile sample is in the interface and delamination appeared at high annealing temperature (450 °C).

Fabrication of glass/carbon fiber-reinforced Al-based composites through deformation bonding

The goal of the present study is to fabricate the short fiber-reinforced metal matrix composites by accumulative roll bonding. Various mixtures of fibers including 100 glass, 95 glass/5 carbon and 80 glass/20 carbon (all in wt.%) were used as the reinforcement. In order to investigate the bonding quality at layer interface, the composites with various fiber mixtures were produced by cold roll bonding. The bonding strength of the composites under different processing conditions including the fiber mixture, reduction in thickness and post-rolling annealing was measured by the peeling test. The 95 glass/5 carbon mixture was used to fabricate the fiber-reinforced composite through accumulative roll bonding. The fiber distribution, tensile properties and wear behavior of the composite were investigated at various numbers of accumulative roll bonding cycle. It was found that during accumulative roll bonding, the fiber clusters were broken and fragmented into smaller pieces. Results showed that the tensile strength and wear resistance of the composite enhanced with increasing the number of accumulative roll bonding cycles.