cementite

It is the iron that displays white fractured surface due to the presence of cementite.

After cementite is formed, the integrity of the disc is compromised.

When given more time, stable microconstituents can form: ferrite and cementite.

"White" cast irons contain their carbon in the form of cementite, or iron-carbide.

When slowly cooling a hypereutectoid steel, the cementite will begin to crystallize first.

Austenite is formed by withdrawal of carbon atoms from cementite into ferrite.

Similar iron carbides occur also in technical iron alloys and are called cementite.

The softer core is some combination of ferrite and cementite, such as pearlite.

Cementite is unstable and breaks down between 600-1100 C into ferrite and carbon, so working the hot metal must be done very carefully.

The best known is cementite, FeC, which is present in steels.

Likewise steels with higher carbon contents will form cementite before reaching the eutectoid point.

For a low carbon steel, typically discontinuous "stringers" or small particles of cementite will be present between laths.

For steels that have more than 0.8% carbon the cooled structure takes the form of pearlite and cementite.

Further heating reduces the martensite even more, transforming the unstable carbides into stable cementite.

It can be wear resistant because of a strong lamellar network of ferrite and cementite.

The only diffusion that occurs by this theory is during the formation of the carbide phase (usually cementite) between the ferrite plates.

Rapid cooling partly or completely suppresses graphitization and leads to formation of cementite, which is called white iron.

Since cementite is essentially a ceramic, this also accounts for the famous sharpness of the Damascus (and bulat) steel.

The steel is then quenched (heat drawn out) at a high rate causing cementite to precipitate and finally the remaining pure iron to solidify.

This austenisation of white iron occurs in primary cementite at the interphase boundary with ferrite.

The purposes of both tempering methods is to cause the cementite to decompose from the ledeburite, increasing the ductility.

Since cementite is much harder than pearlite, the alloy has greater hardenability at a cost in the ductility.

The steel then becomes heterogeneous, being formed of two phases; the carbon (carbide) phase cementite, and ferrite (iron).

In lower bainite, cementite nucleates on the interface between ferrite and austenite.

"I think," said Hoddan, "that we can make an electronic field that'll soften the cementite between the crystals of steel, without heating up anything else.