Valve seat inserts of sintered ferrous materials

摘要

Sintered ferrous materials are described having a composition in wt % lying within the ranges of C 0.8-1.5/W 1-4.4/Mo 1-4.4/V 1-2.6/Cr 1.3-3.2/Others 3 max./Fe balance. The material may be made by a method comprising the steps of mixing between 40 and 70 wt % of a powder having a composition in wt % within the ranges C 0.45-1.05/W 2.7-6. 2/Mo 2.8-6.2/V 2.8-3.2/Cr 3.8-4.5/Others 3.0 max./Fe balance with between 60 and 30 wt % of an iron powder and from 0.4 to 0.9 wt % of carbon powder, pressing a green body of the article from the mixed powder and then sintering the green body. The material may optionally contain sulphur, metallic sulphides. The material may be infiltrated.