| 摘要 |
PURPOSE: To improve the wear resistance, e.g. of a sliding part of a fuel injection valve for alcoholic fuel and to increase its durability. CONSTITUTION: As material for a valve seat 2 and a valve 3, a steel material, having a composition consisting of, by weight, 1.0-3.0% C, <=1.0% Si, <=1.0% Mn, 9.0-20.0% Cr, Mo and/or W in the range satisfying Mo+1/2W=1.0 to 10.0%, V and/or Nb in the range satisfying V+1 /2Nb=1.0 to 6.5%, 1.0-5.0% Co, and the balance essentially Fe and also having >=63 HRC hardness after heat treatment and <=10μm average carbide grain size in a matrix, is used. Further, as a stopper member 5, an austenitic stainless steel, which is free from hard fine grains of carbide, etc., of >=1000 Vickers hardness and in which the hardness of the base material is regulated to >=170 Vickers hardness, is used.
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