Patent ID: 9334977
Filing Date: 2016-05-10
CPC Classification: C22C,C23C,F01L,F16K

Claim Text:
1. An engine valve including an engine valve base body having a stem portion and a head portion provided at one end portion of the stem portion, which engine valve comprises: a build-up portion formed by seat welding to encircle the head portion; and a seat obtained by forming a surface-hardened layer on the build-up portion, wherein the build-up portion is formed of a seat weld material constituted of a Ni—Fe—Cr alloy containing W at 8.0 to 40.0 mass %, Mo at a total together with W in a range of 20.0 to 40.0 mass %, Fe at 20.0 to 50.0 mass %, Cr at 12.0 to 36.0 mass %, B at 1.0 to 2.5 mass %, and a balance of Ni and inevitable impurities, and wherein the surface-hardened layer is formed by effecting nitriding treatment on the entire valve to form a nitride layer on a machined surface formed on the seat.