Interfacial Characteristics of 6061/AZ31B Composites in Multi-Pass Rolling

An Al 6061/Mg AZ31B composite plate with good bonding and excellent comprehensive mechanical properties was prepared through solid-liquid cast-rolling bonding (SLCRB). The microstructure evolution and mechanical behavior of Al/Mg composite plates under different rolling passes were studied. The results showed that with the increase of rolling passes, the bonding layer of the composite plate was crushed, and the base material on both sides of the substrate gradually grew towards the broken part of the bonding layer. The microstructure on both sides of the substrate extended along the rolling direction and was dynamically recrystallized to a certain extent. In the Mg substrate, because the preheating temperature was higher than its recrystallization temperature, with the increase of rolling passes, the grains in Mg substrate were crystallized. When the rolling passes reached the fourth pass, complete recrystallization basically took place in the Mg substrate. With the change of the internal structure and bonding layer on both sides of the substrate, the mechanical properties of the composite plate can be improved gradually. The tensile strength increased from 136 MPa before rolling to 190 MPa at the fourth pass, and the shear strength increased from 74 MPa to 98 MPa, with growth rates of about 40% and 32%, respectively. The elongation of the composite plate decreased from 6.3% to 5.4%, a decrease of about 1%.