The Development of a New Austenitic Stainless Steel Exhaust Valve Material

The durability requirements of the diesel engine exhaust valve have been satisfied through the use of several iron, nickel, and cobalt base alloys. There have been cases where iron base austenitic alloys were found deficient in one or more physical or mechanical properties, and they were replaced with a nickel or cobalt base super alloy, often with a wide margin of design safety. Strategic alloying elements such as cobalt, tungsten, and nickel have escalated in price at a significant rate, thus increasing the cost of the super alloys. An improved austenitic alloy has been developed to provide adequate performance while retaining the cost effectiveness of iron base systems. During this development program, the alloy was designed to minimize its susceptibility to manufacturing problems which have been associated with prior valve materials.