COMPOSITE SLEEVE MADE OF SINTERED HARD ALLOY

PROBLEM TO BE SOLVED: To stably manufacture a composite sleeve made of a sintered hard alloy that the outer layer is constituted of a WC base sintered hard alloy having high wear resistance and inner layer is constituted of steel, and to prevent the breakage of the sleeve due to the generation of heat cracks at the time of rolling and to reduce the number of processes in a rolling process. SOLUTION: This sleeve is the composite sleeve made of the sintered hard alloy that the outer layer consisting of the WC base sintered hard alloy is formed on the outer periphery of the inner layer whose metallographic structure consists of the steel composed of perlite alone substantially or substantially the perlite and ferrite of =1.2. The compressive residual stress in the circumferential direction in the central part in the direction of the axis of rotation of the sleeve of the outer layer consisting of the WC base sintered hard alloy is 15-60 kg/mm2 at the normal temperature.