Iron-based sintered alloy for valve seat, and valve seat for internal combustion engine

Abstract

It is an object of the present invention to provide a valve seat product in which the amount of hard particles added to improve the wear resistance of a valve seat of an internal combustion engine is increased, and is excellent in the mechanical strength and machinability. In order to achieve the object, an iron-based sintered alloy material for a valve seat is employed which is made to contain a first hard particle having an average primary particle diameter of 5 to 20 μm and a second hard particle having an average primary particle diameter of 20 to 150 μm in a texture, wherein a particle size distribution curve measured by laser diffraction scattering analysis has N peaks (N is an integer equal to or larger than 2) and when particle diameters corresponding to the peak top positions are denoted as Dto D, a peak top particle diameter difference between neighboring Dand D(|D−D|: n is an integer equal to or larger than 2 and equal to or smaller than N) is in the range of 15 to 100 μm in at least one neighboring Dand D; and the total area ratio occupied by both of the first hard particle and the second hard particle constituting the mixed hard particle in the texture of the iron-based sintered alloy is 10 to 60% by area.