Patent ID: 9714724
Date: 2017-07-25
CPC Classifications: B22F,C22C,C22F,F01L,F16K,Y10T

Claim:
1. A method of manufacturing an exhaust valve spindle for an exhaust valve in an internal combustion engine, which exhaust valve spindle has a shaft and a valve disc at a lower end of the shaft, which valve disc has an upper surface and a seat area at the upper surface, comprising the steps of a) providing the valve disc of a base material, which valve disc is shaped with an annular recess in its upper surface, which recess extends a distance down below the upper surface of the valve disc, b) providing in the recess a valve seat material of a nickel-based alloy, wherein the alloy, stated in percent-by-weight and apart from common impurities and inevitable residual amounts of deoxidizing components, comprises at least from 34.0 to 44.0% Cr, an aggregate amount of Nb and Ta in the range from at least 2.8 to 6.1%, from 0.3 to 2.0% Ti, at the most 0.2% Al, at the most 0.04% B, at the most 0.8% Fe, at the most 0.04% C, at the most 0.4% Si, and a balance of Ni, where the amount of Ti+Nb+0.5×Ta is in the range from 3.4 to 6.6%, and where the amount of Nb+0.5×Ta is less than 3.0% if the amount of Ti is larger than 1.5%, c) performing cold deformation in the seat material, and d) subjecting the valve disc to a heat treatment causing hardening by precipitation of γ″ (Ni