On the Phenomena of Graphite Precipitation of Calcium Graphite Steel

Abstract

The process of graphite precipitation in hypereutectoid steels containing 1.5 to 1.7%C has been investigated by thermal analysis, dilatometric measurement and microstructural observation of water-quenched specimens. The results may be summarized as follows: (1) Any change due to graphite precipitation has not been ascertained by means of thermal analysis. The increased Si contents due to Fe-Ca alloy addition rises in Ar₁ transformation more than that found in untreated steels. (2) In the dilatometric measurement the graphite precipitation occurs remarkably in the range of the Agr to the A₁ transformation. However, if the amount of Fe-Ca alloy added increased, graphitization was also confirmed slightly above the Ac₁ transformation in the process of heating and then showed ferrite formation under the Ar₁ transformation in the process of cooling. The shape of the separated graphite by reheating was no longer spheroidal, but became a massive state.