Factors Affecting Graphitization Of Cast Iron

The formation process of graphite in cast iron is called graphitization process.

It can be divided into three stages:

1.Liquid phase hypoeutectic crystallization stage.It include the direct crystallization of primary graphite from the liquid phase of hypereutectic components, the crystallization of austenite from the liquid phase of eutectic components and the graphite formed by primary cementite decomposed during high temperature annealing.

2.Eutectic transition phases between hypoeutectoid transitions.It include the direct precipitation of secondary graphite from austenite and the graphite formed by the decomposition of secondary cementite in this temperature range.

3.Co-folding transition stage.Including the eutectoid graphite formed during the co-folding transformation and the graphite formed by the decomposition of the eutectoid cementite during annealing.

The structure of cast iron depends on the degree of graphitization. In order to obtain the required structure, the key is to control the degree of graphitization. Practice has proved that many factors such as the chemical composition of cast iron, the cooling rate of cast iron crystals, the overheating and standing of molten iron, etc., all affect graphitization and the microstructure of cast iron.

Factors affecting graphitization of cast iron:

1.Influence of chemical composition.

2.Influence of cooling rate.

3.The effect of overheating and high temperature standing of cast iron.