Impact of Cooling Character on Structure and CTE of Cast Invar Alloy Made from Secondary Raw Materials

Abstract

Metallography analysis of invar alloys made from secondary raw materials and crystallized with different cooling rates has been carried out. The study has demonstrated that velocity of crystallization has an impact on the dispersity of graphite. The higher velocity of cooling, the more dispersive graphite is. The volume percentage of graphite in alloy, crystallized with high cooling rate, is lower than compared with low cooling rate. Crystallization with low cooling rate leads to the reduction of the amount of carbon into γ-phase. The coefficient of thermal expansion is basically depends on the amount of carbon into γ-phase.