Niobium in heat resisting cast steel auto parts

The Casting Technology Research Laboratory at Hitachi Metals Ltd. developed a heat-resisting cast steel specifically directed at the automotive engine’s exhaust systems. The new steel, HERCUNETE-S A3N, is an austenite cast steel having the chemical composition of 20%Cr-10%Ni-3%W-2%Nb was found to have the highest strength at over 600°C and exhibited the highest oxidation resistance at 900°C. Additionally, it was found to have a high thermal fatigue strength greater than Niresist D5S of an austenite cast iron structure. Due to the excellent properties at such elevated temperatures typical for exhaust gases, this developed cast steel grade was applied for exhaust manifold and turbine housings. (AU)