Interfacial Bonding Behavior and Mechanical Properties of a Bimetallic Ring Blank Subjected to Centrifugal Casting Process

The vertical centrifugal casting of 40Cr/Q345B bimetallic ring blank was conducted. The effects of pouring intervals of the inner and outer layers’ liquid metal and rotate speed of casting mold on the bonding interface of bimetallic ring blank were studied. The three-dimensional microstructures and the resultant mechanical properties were clarified with the optimum processing parameters. The results indicate that the heat dissipation of the outer layer increases with the increasing intervals, and the metallurgical bonding of the inner and outer layers become more difficult. As the rotate speed increases, the degree of convective heat transfer in molten metal increases, leading to the poor bonding interface. The interval of 170 s and rotate speed of 700 r/min are recommended as the optimum parameters, under which the close bonding interface is obtained. The mold filling of vertical centrifugal casting is characterized by a lamellar flow of liquid metal from the outer to inner layers and from the bottom to top surface under the coupling of gravity, centrifugal force and Coriolis force. Due to the slight effect of gravity on the CD-RD section, the bonding interface is wider under the CD-RD section compared to that under the AD-RD section. The sufficient metallurgical bonding between the outer and inner layers is indicated by the diffusion of Cr, C and Mn. The tensile and shear strength along different directions meet the required properties of composited materials. The fracture mechanism in the outer and inner layers is characterized by the brittle fracture and ductile fracture, respectively.