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The demands on valve seat insert materials, in terms of providing greater wear-resistance at higher temperatures, enhanced machinability and using non-environmentally hazardous materials at a reasonably low cost have intensified in recent years. Due therefore to these strong demands in the market, research was made into the possibility of producing a new valve seat insert material. As a result a high speed steel based new improved material was developed, which satisfies the necessary required demands and the evaluation trials, using actual gasoline engine endurance tests, were found to be very successful.

Against the background of environmental problems, the market for variable nozzle turbochargers, which enable countermeasures for improved fuel economy and exhaust gas regulations, has grown rapidly in recent years. Because the nozzle ring is a main part which is used under a particularly severe temperature environment, even among turbocharger parts, high Cr cast steel is generally used. In response to market needs for further improvement in heat resistance and cost reduction, EW-50 which has heat resistance and wear resistance was developed, as this material is suitable for parts such as nozzle rings. EW-50 has higher wear resistance and oxidation resistance than the conventional high Cr cast steel over the entire temperature range up to 1323K. As EW-50 also makes it possible to reduce costs by near net shape production, its large potential for application to variable nozzle-type turbocharger parts was confirmed.