Power-matallurgy valve seat inserts

Abstract

A powdered metal blend mixture for making a powdered metal part especially a valve seat insert. The mixture includes 15 to 30 wt.% of a valve steel powder, 0 to 10 wt.% nickel, 0 to 5 wt.% copper, 5 to 15 wt.% of a ferro-alloy powder, 0 to 15 wt.% of a tool steel powder, 0.5 to 5 wt.% of a solid lubricant, 0.5 to 2 wt.% graphite, 0.3 to 1.0% of a temporary lubricant, and the balance being substantially a low alloy steel powder containing 0.6 to 2.0 wt.% molybdenum, 0 to 5 wt.% nickel, and 0 to 3.0 wt.% copper. The present invention provides improved high temperature wear and corrosion resistance over prior art materials as well as improved machinability. The blend of the present invention provides a relatively high density material that allows for a single press and sinter technique.

Description

technical field [0001] This invention relates to metal powder mixtures, and more particularly to a new and improved metal powder mixture for use in the manufacture of automotive parts such as valve seat inserts. Background technique [0002] The principles of the working cycle of internal combustion engines are well known in the art. The physical properties required for effective fit of intake and exhaust valves, valve sleeves, and seat inserts for sealed combustion have also been extensively studied. [0003] Wear resistance is an essential requirement for valve seat inserts used in internal combustion engines. In an effort to obtain a good combination of heat and corrosion resistance, machinability, and wear resistance, castings of cobalt, nickel, or martensitic iron-based alloys have been used to manufacture exhaust valve seats inserts. Because of the presence of wear-resistant carbides in cast alloys, these alloys are generally superior to austenitic heat-resistant st...

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