Effects of composition and structure on the state, fatigue, and damping properties of high-strength cast iron

Abstract

Measurements have been made on the ultimate strength, yield stress, endurance limit with and without stress concentrators, and oscillation decrement for cast iron containing spheroidal graphite and alloyed (in mass %) with 0.30–1.08 Mn, 0–0.81 Cu, 0.45–0.62 Ni, and 0–0.32 Mo and having structures of ferrite, pearlite, bainite, and bainite-ferrite types (with 25–30% ferrite) and also martensite structure. Concentrations of those elements have been determined that provide the best combination of static and dynamic characteristics. The effects of the alloying elements on the properties of the cast iron have been related to the structure of the metal substrate. In particular, in pearlitic cast iron alloyed with 0.7–0.8% Cu, 0.4–0.5% Ni, 0.3% Mn, the addition of Mo is ineffective, while in cast iron having the bainite structure, that element raises the yield stress and the fatigue strength even in the absence of Cu, while the sensitivity to stress concentration is reduced.