On the Process of Graphite Precipitation of Calcium Graphite Steel

Abstract

The effect of calcium on the graphite precipitation from the γ phase of the hypereutectoid steel has been examined by a new apparatus for the measurement of solidifying contraction. It has been ascertained that the graphite precipitation in the solidifying process occurred over a range from the vicinity of the saturation curve E′S′ of the γ phase (Agr transformation) to the A₁ transformation and graphitization was most remarkably near the A₁ transformation. A large amount of metallic Ca or Fe-Ca alloy addition greatly affected the solidifying contraction curve, leading to a considerable expansion due to ferrite segregation near the A₁ transformation. In this case the rise of the A₁ transformation was not observed, although Si contents increased. The addition of Fe-Ca alloy as the graphitizing agent increased the amount of residual calcium more than that determined by metallic Ca.