Solidification Sequence of Multi-Component White Cast Iron

Abstract

  The solidification sequences of multi-component white cast irons containing different types of carbides were investigated by means of thermal analyses and quenching tests. In the case of cast iron with MC and M₂C eutectic carbides, first austenite (γ) phase or MC carbide precipitates as a primary phase, then the L→γ+MC eutectic reaction takes place and finally, the solidification finishes by the L→γ+M₂C eutectic reaction. In cast iron in which MC and M₇C₃ carbides coexist, the solidification begins with the precipitation of the primary γ phase or MC carbide, followed by the L→γ+MC eutectic reaction goes, and then the L→γ+M₇C₃ eutectic reaction. As for cast iron with MC, M₇C₃ and M₂C eutectic carbides, the solidification sequence is as follows : L₀→γ+MC+(L₁), L₁→γ+M₇C₃+(L₂) and L₂→γ+M₂C. EDS analyses of alloy concentrations in the liquid regions of the quenched sample demonstrated the propriety of each eutectic reaction during solidification.