Nittan Valve Co., Ltd.

Fukuda Metal Foil & Powder Co., Ltd.

Masanami Iio

Shinichi Nishimura

Katsunori Otobe

Hisanaga Yokoyama

Kenji Nakagawa

A hard-facing alloy having impact resistance, wear resistance and hot corrosion resistance and containing Fe which is a bountiful resource and inexpensive is provided. Provided are: a Ni&#x2014;Fe&#x2014;Cr alloy containing 0 to 20.0 mass % of Mo, 8.0 to 40.0 mass % of W, 20.0 to 40.0 mass % of a total amount of Mo and W, 20.0 to 50.0 mass % of Fe, 12.0 to 36.0 mass % of Cr and 1.0 to 2.5 mass % of B, and the remainder being Ni and unavoidable impurities; and an engine valve welded with the same alloy. The above Ni&#x2014;Fe&#x2014;Cr alloy can further contain 15 mass % or less of a total amount of elements selected from Co, Mn, Cu, Si and C, in such cases, 15.0 mass % or less of Co, 5.0 mass % or less of each of Mn and Cu, 2.0 mass % or less of Si and 0.5 mass % or less of C are preferred.

Ni&#x2014;Fe&#x2014;Cr alloy and engine valve welded with the same alloy

[Problem] To provide an engine valve which satisfies predetermined characteristics with respect to impact resistance, abrasion resistance and high-temperature corrosion resistance all of which meet or exceed predetermined levels required to resist severe use environments, while also minimizing the content ratios of predetermined rare metals. [Means for Solving the Problem] An engine valve is configured to include 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&#x2014;Fe&#x2014;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, thereby ensuring predetermined characteristic while minimizing rare metal content ratio.

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Hadano, Japan

Masanami Iio