发明申请

EXHAUST POPPET VALVE AND SOLUTION HEAT TREATMENT METHOD OF THE SAME
摘要:
Object of the Invention The invention provides a forged exhaust poppet valve and a method of solution heat treating the same, in which only a predetermined portion of the valve is subjected to the solution heat treatment so as to provide the seat portion of the valve with satisfactory wear resistance, and a predetermined transitional neck-stem region with satisfactory high-temperature creep strength.Means for Achieving the Object An exhaust poppet valve (10) comprises a head portion (12) which has a seat portion (14) on the outer periphery thereof and is integral with the diametrically tapered neck portion (16) of a stem portion (18) of the valve. Using a radio-frequency heating apparatus, a solution heat treatment is given to a predetermined transitional region (A) defined between the neck and stem portions that is exposed to exhaust air during a valve opening period so that the grain size in the region (A) is controlled not to exceed ASTM 10. Thus, not only required high-temperature creep strength is secured in the transitional neck-shaft region (A) but also necessary hardness (wear resistance) is secured in the seat portion (14) of the valve (10), thereby rendering the exhaust poppet valve highly durable.
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