عنوان مقاله [English]
In recent years, multi layered composite have been attention of many researchers and different industries. Cold roll bonding (CRB) is one of the method for produce layered composite that compared to other composite manufacturing methods are more economically and have the ability to produce layered composite with different material. In the present study, Al/Cu/Mg layered composite was produced through CRB method at room temperature, without lubricant and via using laboratory rolling machine by applying 60\% reduction in thickness and plane stress fracture toughness was investigated experimentally, by R curve method for initial aluminum, copper, magnesium and Al/Cu/Mg composite. Results showed that the value of plane stress fracture toughness
depends on both strength and ductility. Also, fracture toughness of produced layered composite reached 32.1, which increased 3.24, 2.18 and 2.73 times, respectively, compared to the initial samples of aluminum, copper and magnesium. In addition to investigations of the plane stress fracture toughness, mechanical properties, fracturgraphi and microstructure investigated through uniaxial tensile test, microhardness measurement, and scanning electron microscope (SEM) and optic microscope (OM). Results of carried out tests, showed the value of ultimate tensile strength (UTS) and microhardness for Al/Cu/Mg layered composite compared to initial Al 1050, pure Cu and Mg AZ31B increased but the elongation decreased sharply, that the main cause of these increase and decrease are applied high strain and cold working. Value of ultimate tensile strength for Al/Cu/Mg layered composite received 220.3 MPa that compared to initial Al 1050 and pure Cu and Mg AZ31B, 144\%, 23\% and 29\% enhanced, respectively. Also microhardness calculated for each layers of composite individually and for initial Al 1050, pure Cu and Mg AZ31B increased 136\%, 84\% and 41\%, respectively. Results of SEM demonstrated that ductile fracture mechanism govern for Al and Cu layers but fracture surface of Mg layer is absolutely brittle fracture.