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When CNG, LPG, and other gas fuels were used for combustion in vehicles' engines, a large degree of valve seat wear was observed and it was difficult to provide the same wear resistance as for gasoline engines. Therefore, the mechanism of valve seat wear in gas fuel engines was analyzed and an alloy valve seat was developed. In addition to converting the matrix to an alloy, Co-Mo-Cr was used for the self-lubricating effect present in its hard particles. Also, in order to improve machinability, which is inversely related to wear resistance, a sintered alloy valve seat containing MnS was developed. As a result, wear resistance equal to that for gasoline engines was achieved.

Honda has developed, in collaboration with Hitachi Metals and Daido Steel, two types of low-nickel heat-resistant alloys for exhaust valves which are more cost effective than the conventional nickel alloys. They are NCF4015 that contains approximately 40% nickel and NCF3015 with approximately 30% nickel content. The two types of new alloys were developed based on our unique alloy design concept. Both alloys feature superb high-temperature strength and are capable of maintaining favorable material properties, even after an high-temperature exposure. The NCF4015 is compatible with the conventional Inconel 751 and 60Ni alloys in terms of high-temperature strength. The NCF3015 falls slightly behind the two metals, but overwhelms the 21-4N (SUH35) in high-temperature strength. The exhaust valves made of the two alloys developed have been used for mass production engines.