Cast iron: the role of carbon and silicon

Cast irons are ternary iron-carbon-silicon alloys. Cast irons are ternary iron-carbon-silicon alloys:
Cast irons are ternary iron-carbon-silicon alloys;
Cast irons are ternary iron-carbon-silicon alloys;
Cast irons are ternary iron-carbon-silicon alloys with spherical graphite;
with spherical graphite.

 

with spherical graphite

with spherical graphite, with spherical graphite. In white cast irons, carbon is present in the form of cementite Fe3C.

In white cast irons, carbon is present in the form of cementite Fe. Increasing the silicon content makes it more difficult to form cementite and, thereby, Increasing the silicon content makes it more difficult to form cementite and, Increasing the silicon content makes it more difficult to form cementite and.

Increasing the silicon content makes it more difficult to form cementite and

When working with cast irons, the concept of carbon equivalent is often used.. When working with cast irons, the concept of carbon equivalent is often used.:

The figure below gives a graphical representation of the ratio of carbon and silicon content in various types of cast irons..

The figure below gives a graphical representation of the ratio of carbon and silicon content in various types of cast irons.Picture 1 The figure below gives a graphical representation of the ratio of carbon and silicon content in various types of cast irons.
for various types of cast irons and silicon steels

Note, for various types of cast irons and silicon steels, for various types of cast irons and silicon steels 4,3 %. The dotted line at the bottom of the figure reflects the relationship CE = 2,0 % – The dotted line at the bottom of the figure reflects the relationship CE =.

The dotted line at the bottom of the figure reflects the relationship CE =, in which there is no silicon at all. in which there is no silicon at all 4,3 %. in which there is no silicon at all phase diagram on the image 2 it is seen, that this composition is exactly the eutectic composition for iron-cementite alloys and is very close to the eutectic composition for iron-graphite alloys.

that this composition is exactly the eutectic composition for iron-cementite alloys and is very close to the eutectic composition for iron-graphite alloysFigure - Combined phase diagram of iron-graphite and iron-cementite

Figure - Combined phase diagram of iron-graphite and iron-cementite 1 is a good interpretation of the change in the eutectic composition with increasing silicon content in iron-carbon alloys. is a good interpretation of the change in the eutectic composition with increasing silicon content in iron-carbon alloys, is a good interpretation of the change in the eutectic composition with increasing silicon content in iron-carbon alloys, which is close to eutectic, which is close to eutectic. It means, which is close to eutectic 4,3 %, then the volume fraction of the solid phase in the form of dendrites increases. Likewise, then the volume fraction of the solid phase in the form of dendrites increases 4,3 %, then the volume fraction of the solid phase in the form of dendrites increases + then the volume fraction of the solid phase in the form of dendrites increases, or austenite + or austenite.

or austenite4-or austenite

or austenite

 

Source: John D. Verhoeven, Steel Metallurgy for Non-Metallurgists, 2007