Abstract: A method is provided that in one embodiment is operative to form a wear resistant coating of titanium nitride on the outer surface of a metal valve such as an internal combustion engine poppet valve (100). In another embodiment, the method is operative to provide a valve made from titanium with an in situ zone of titanium nitride extending inwardly from the valve's outer surface. In yet another embodiment, the method is operative to provide a valve made from titanium with both a coating of titanium on the valve's outer surface and an in situ zone of titanium nitride extending inwardly from the valve's outer surface.

Abstract: A process for providing an engine valve (2) with varied microstructure grain size is provided. The process includes the steps of: providing a slug (4) of suitable metallic valve composition having a grain size of less than about A.S.T.M. 8; solution heat treating slug (4) to provide a larger grain size and to substantially dissolve carbonitride stringers if present; and forging the solution heat treated slug (4) in a manner that provides a substantially uniformly distributed A.S.T.M. grain size of about 1 to about 7 in a central region beneath the combustion face of head (14) of valve (2) while cold working a seat face (16) on head (14) and extruding the stem (10) of valve (2) such that its microstructure grain size is less than about A.S.T.M. 8.