| 摘要 |
<p>This invention provides a coolant-containing hollow poppet valve, which, in use, in consideration of a temperature distribution caused in each pert of the valve, causes a lowering in fatigue strength and creep strength in the valve at its site exposed to high temperatures falling within the tolerante of design standard, and, in consideration of required properties at the other valve sites, holds abrasion resistance and strength, and a process for producing the same. An improvement in heat resistance, abrasion resistance and strength depending upon properties required in each site can be realized by conducting a cold drawing step and an intermediate annealing step to bring the Vickers hardnesses of a cylindrical shaft portion (12) and a fillet-shaped head portion (14) open in a flare form to the other end of the shaft portion (12) to approximately not less than 250 Hv and not more than 350 Hv, and approximately not less than 350 Hv, respectively, and conducting cold pressing to bring the Vickers hardness of a seat portion (15) in the outer periphery of the opening to not less than 380 Hv.</p> |
