Iron-base sintered alloy material for valve seat insert and method for manufacturing the same

A method for manufacturing an iron-base sintered alloy material for a valve seat insert, comprising:

• blending and mixing, as raw material powder, iron-based powder, hard-particle powder, powder for an alloy, and optionally solid-lubricant particle powder to obtain mixed powder;
• putting the mixed powder into a mold for molding to obtain a green compact having predetermined shape and density;
• and
• sintering the green compact to obtain a sintered body, wherein
• the hard-particle powder contains first hard-particle powder and second hard-particle powder,
• the first hard-particle powder is Co base inter-metallic compound particle powder having an average particle diameter of 50 to 60 μm, Vickers hardness of 600 to 1200 HV,
• the second hard-particle powder is high-speed tool steel-based, carbide-containing particle powder having Vickers hardness of 400 to 700 HV, and
• the raw material powder is blended such that a matrix part including a matrix phase and hard-particles after sintering contains 0.3 to 1.5% by mass of C, and 10 to 50% by mass in total of one or more kinds selected from Si, Mo, Cr, Ni, Co, Mn, S, W, V, Ca, F, Mg, and O, the balance being Fe and unavoidable impurities, and a structure after sintering includes 25 to 45% by mass of the first hard-particles and 2 to 30% by mass of the second hard-particles, in which 35 to 50% by mass in total of these two kinds of hard-particles are contained, to obtain the sintered body having a density of 6.6 g/cm3 or more and radial crushing strength of 350 MPa or more.