To provide a sintered alloy-made valve seat excellent in wear resistance and coming-off resistance and a method of manufacturing this valve seat.
In a valve seat press fitted to a cylinder head comprising two layers of upper/lower members integrally formed by sintering, porosity of the upper member is less than 5% and of the lower member is 5% or less by a volumetric efficiency further with a different composition from the upper member, in a sintered alloy. A hard particle is 5 to 25% dispersed by an area coefficient. A metal mold is charged with material powder respectively for the upper/ lower members, the powder is compressed and molded, an integral pressure powdery unit comprising the upper/lower two layers is formed, next to be heated and sintered in the protecting atmosphere, and after applying softening annealing, high density molding is performed by rotary forging. Thereafter, resintering is performed, quenching and tempering, are performed, a valve seat is obtained by cutting and grinding.
SATO TOSHIAKI
TANNO MIZUNARI
