Forming limit diagrams and mechanical properties of AA1050/Ti CP2 multilayered composite produced by the accumulative roll bonding technique

Abstract

In this study, the AA1050/Ti CP2 metallic multilayered composite was produced by accumulative roll bonding (ARB) using AA 1050 and commercially pure titanium Ti (CP-Ti ASTM grade 2) for three cycles at ambient temperature. The microstructure evolution was investigated by scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). Also, the tensile test and Vickers microhardness measurement were conducted to evaluate mechanical properties. The forming limit diagrams (FLD) were obtained for a metallic multilayered composite for the first time by the Nakazima test. It was observed that a continuous and well-bonded composite was fabricated after the first cycle. For the subsequent two cycles, necking and fracture of Ti reinforcement occurred in the Al matrix. The maximum tensile strength was reached after two cycles with almost a 98% increase compared to the annealed aluminum sample. However, the tensile strength was reduced after the third cycle. The uniform elongation considerably decreased after the first cycle and was maintained for the subsequent two cycles. The microhardness improved by 124% and 47% for Al and Ti, respectively, in the whole process of ARB in comparison with annealed Al and Ti. As a formability criterion, the level of forming limit curve (FLC) was reduced sharply after the first ARB cycle. For subsequent cycles, this reduction was neglectable. The Al/Ti composite fracture surfaces were a combination of shear ductile and brittle after the third pass.