Effect of Vacuum Degrees on Interfacial Bonding Behavior of 7050 Aluminum Alloy Clad Plates During Hot-Roll Cladding

Interfacial bonding behavior of 7050 aluminum alloy clad plates during hot-roll cladding under different vacuum degrees was investigated. The results demonstrated that the bonding effect of the interface was positively correlated with the vacuum degree. Due to severe surface oxidation at 105 Pa, the metal on both sides of the interface did not undergo metallurgical bonding and mainly maintained physical contact, with an ultimate tensile strength (UTS) of only 209 MPa across the interface. At 102 Pa, the large-scale migration of original interfacial grain boundary was still inhibited and continuous dynamic recrystallization occurred mainly at the interface with bulging only locally, which directly led to brittle fracture. At 10-1 Pa, significant discontinuous dynamic recrystallization (DDRX) occurred at the interface, resulting in the complete elimination of the original interface. And UTS across the interface was 338 MPa, reaching the level of the matrix. Therefore, interfacial metallurgical bonding could be achieved by reducing the oxidation of interface and further inducing DDRX during hot-roll cladding.