HEAT RESISTING CAST IRON AND EXHAUST SYSTEM PART THEREFROM

摘要

A heat resisting cast iron containing graphite for use in exhaust system parts used at temperatures exceeding 800°C, which heat resisting cast iron comprises, on weight basis, 3.5 to 5.6% of Si and 1.2 to 15% of W, having an interlayer with W and Si concentrated therein on boundaries of graphite and the base structure. Exhaust system parts comprised of this heat resisting cast iron have an AC1 transformation point, as measured while raising temperature from 30°C at a rate of 3°C/min, of 840°C or higher and exhibit a thermal crack life of 780 cycles or more at a thermal fatigue test in which heating and cooling are performed under such conditions that the upper limit temperature is 840°C, the temperature amplitude 690°C and the constraint ratio 0.25.