Study on Interface Bonding Behavior and Quality Control of 40Cr/Q345B Bimetallic Ring Blank in Vertical Centrifugal Casting

In this study, the vertical centrifugal casting was used to produce a bimetallic ring blank with an outer layer of 40Cr and an inner layer of Q345B. The effects of the pouring temperature of the outer layer, rotational speed of the casting mold, pouring temperature of the inner layer and pouring intervals of the inner and outer layers on the interface bonding behavior of the bimetallic ring blank were studied. The axial maximum temperature difference in the inner surface of the outer layer first decreased and then, increased with increasing pouring temperature of the inner layer, and first, increased and then, decreased with increasing rotational speed. The pouring temperature of 1570 °C in the outer layer and rotational speed of 800 r/min were recommended as the optimum parameters for the outer layer, which contributed to minimum temperature difference in the axial direction of the inner surface of the outer layer. Increasing the pouring temperature of the inner layer effectively reduced the defects of porosity caused by interfacial shrinkage, but the effective stress at the bonding interface was enhanced. As the pouring intervals increased, metallurgical bonding at the interface became more difficult, which led to poor quality at the bonding interface. A pouring temperature of 1600 °C in the inner layer and a pouring interval of 221 s were recommended as the optimum parameters for the inner layer, and they contributed to sound interface bonding. Under the optimum centrifugal casting parameters, the transition area was characterized by a serrated/canine-shaped interface and obvious diffusion of elements. The shear strengths measured along different directions met the required properties for the materials. A tight metallurgical bonding interface in the bimetallic ring blank was achieved.