Abstract
To improve the wear resistance of ferritic spheroidal graphite cast iron, the martensite phase was introduced around graphite nodules by induction heating. The wear characteristics of cast iron treated in such a way were then examined by rubbing on annealed 0.6% C steel under dry sliding condition and comparing them with those of ferritic, bull's eye and pearlitic spheroidal graphite cast irons. It was found that the wear resistance of the treated ferritic iron is markedly superior to that of pearlitic spheroidal graphite cast iron which is frequently used as a good wear-resistant material, and moreover the wear of the mating material is reduced by rubbing with the treated iron. The contact pressure at which mild wear turns to severe wear becomes higher by increasing the volume fraction of the martensite phase. Such improvements in wear resistance are assumed to be the result of the martensite phase introduced around graphite nodules preventing deformation of graphite nodules and ferritic matrix on the sliding surface and in the subsurface region and thus suppressing the formation of wear debris. Also as for graphite steel, which contains graphite nodules similar to those of malleable cast iron, the introduction of martensite around graphite nodules resulted in marked improvement of wear resistance.
