Development of Thermal Fatigue Resistant Ferritic Cast Steel for Turbine Housing of Diesel Engine Automobile

In recent years, the temperature of automobile exhaust gas is on a rising trend due to lowering pollutant emissions and improving fuel economy, and exhaust gas temperature reaches as high as 1173K in the case of diesel engine cars. Against this background, Ni-resist D-5S cast iron has been chosen extensively as a turbine housing material for the diesel engine cars. But, Ni-resist D-5S has become a material of great cost volatility due to high Nickel content of 35 mass%, which price is expensive and unstable. On the contrary Ferritic cast steels, which possesses favorable thermal fatigue properties and good material cost stability, are considered to be promising substitutions for the Ni-resist D-5S. However conventional ferritic cast steels have relatively high melting points, which cause poor castability. For this reason, new ferritic cast steel, StarCast DCR3, has been developed by optimizing the chemical composition with keeping of the advantage of castability, productivity high temperature strength, and thermal fatigue properties such as crack and deformation resistance. Therefore, StarCast DCR3 is considered to be an effective material for turbine housing application up to 1173K.