Method of manufacturing nitrided valve seat insert with supersaturated nitrogen surface layer and product thereof

Abstract

A pre-surface hardened valve seat insert and a process for forming a pre-surface hardened valve seat insert useful for insertion into a cylinder head or an engine block of an internal combustion engine. The process comprises the steps of (a) forming the valve seat insert by casting an iron-chromium alloy having no more than 75 weight percent iron and at least 25 wt. % alloying elements, the alloying elements including at least 9 wt. % chromium; (b) precision machining the valve seat insert to precise tolerances so that the valve seat insert can be installed in the cylinder head or the engine block with or without the need for additional seat machining; and (c) treating the valve seat insert to form an exposed wear resistant surface layer of supersaturated nitrogen free of nitride compounds.

Dependencies are inferred from the claim text.