| 摘要 |
PURPOSE:To provide high wear resistance and durability to a valve by using a sintered material having a steel composition contg. specified amounts if C, Cr, P and B and a structure contg. uniformly dispersed hard carbides as the material of a tip. CONSTITUTION:A tip joined to the tip of the stem of a valve for an internal- combustion engine is made of a wear resistant Fe-base sintered material consisting of, by weight 1-5% C, 5-30% Cr, 0.1-3% P and/or B and the balance Fe with inevitable impurities and having a structure contg. uniformly dispersed hard carbides. To the composition may be added 0.5-10% one or more among Mo, W, Nb, Zr, Hf and Ta, 0.1-6% one or more among Mn, Cu and Ni, and 0.1-3% Si. The wear resistance of the tip of the stem is improved by joining the tip, and the life of the engine valve can be prolonged.
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