The progress of valvetrain design and exhaust valve material research for automobiles

Demands for exhaust valve materials are influenced by fuels and valvetrain designs to comply with requirements such as: (1) Improved seat face corrosion / abrasion resistance, (2) High strength for smaller stem designs, and (3) Cost reduction. Honda has been engaged in the development of nickel-base, heat-resistant alloys meeting the demands of performance and cost since the first development of Inconel 751 in 1979. Nickel-base, heat-resistant alloys have superior high temperature strength and corrosion resistance but are quite expensive. To meet the recent increase in demand for reduced costs, we have reviewed the characteristics required for exhaust valve materials and developed a resource conserving, low nickel superalloy. We believe that this newly developed alloy will find increasing usage in future exhaust valves.