Effects of tertiary elements on the critical solidification rate of the flake-undercooled graphite transition of Fe-C alloys

Abstract

This paper reports an investigation about the effects of 0.004–0.108 mass% S, 0.068–1.10 mass%Si, 0.047–0.177 mass%Ti, 0.035–0.078 mass%Zr, and 0.018–0.042 mass%S and 0.047–0.14mass%Mn on the critical solidification rate of the flake-undercooled graphite, Rc, and inter-graphite spacing λ of gray cast iron during an unidirectional solidification method.The specimens had a mass of 150g, a diameter of 24 mm, and a length of 60 mm. The temperature gradient at the solid-liquid interface was 18–21 K/cm. The experimental equations for the relation between λ and R was obtained using regression analysis. As R becomes larger, λ decreases and the transition from flake to undercooled graphite occurs Rc. The Rc value varied with the elements added. The effects of S and Si intricately changed depending on their amount Ti and Zr decreased Rc. Mn has no influence. The temperature gradient at the solid-liquid interface and the amount of surface-active elements also influence Rc.