The connection mechanism of new developed bimetallic centrifugal cast roll with three-layer structure has been studied. The out-layer material of roll is high chromium cast iron

both the middle-layer and inner-layer material are grey cast iron. It has been found that the interface between high chromium cast iron （outer-layer） and grey cast iron （middle-layer） is composed of a dechromiumized layer （transition zone） and a connection zone

there is a decarbonized zone in the middle grey cast iron layer near the interface between this layer and the inner grey cast iron layer.