What is cementite microstructure?

What is cementite microstructure?

Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. The carbide therefore cemented the iron.

What is ferrite microstructure?

Ferrite is a microstructural phase that is soft, ductile, and similar to pure iron. There is a limit on how much carbon can fit in the gaps in the ferrite structure: 0.02 percent carbon at 1,340 degrees F (725 degrees C), but dropping to 0.006 percent (60 PPM) carbon at room temperature.

What is ferrite and cementite?

The alpha phase is called ferrite. Ferrite is a common constituent in steels and has a Body Centred Cubic (BCC) structure [which is less densely packed than FCC]. Fe3C is called cementite and lastly (for us), the “eutectic like” mixture of alpha+cementite is called pearlite. Solidification of steels.

What is the difference between cementite and ferrite?

Ferrite has a body-centred cubic crystal structure and cementite has an orthorhombic unit cell containing four formula units of Fe3C. The phase diagram illustrates the domains in which particular phases or combinations of phases are stable, and contains information about their equilibrium compositions.

What is the difference between martensite and cementite?

Martensite is formed in carbon steels by the rapid cooling (quenching) of the austenite form of iron at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large enough quantities to form cementite (Fe3C).

What is the hardest microstructure?

Martensite
Martensite: the hardest and strongest microstructure, yet the most brittle.

How is ferrite formed?

Alpha ferrite forms by the slow cooling of austenite, with the associated rejection of carbon by diffusion. Delta ferrite is the high temperature form of iron, formed on cooling low carbon concentrations in iron-carbon alloys from the liquid state before transforming to austenite.

Is ferrite or cementite stronger?

Cementite is harder and stronger than ferrite but is much less malleable, so that vastly differing mechanical properties are obtained by varying the amount of carbon.

Is ferrite a ductile?

Ferrite. It has a BCC structure and it is relatively ductile and soft. Hardness varies from 140-200 HB. In ductile irons the ferrite is around the graphite nodule and it can be extended to the grain boundaries.

Does martensite contain ferrite?

Crystalline Structure of Stainless Steels Ferrite, austenite, and martensite are all examples of iron’s crystal structures, and all are found within different types of steel.

How are ferrite and cementite arranged in a carbide?

Pearlite is a product of eutectoid transformation in steel. Its morphology is that ferrite and cementite are arranged in layers like fingerprints. According to the distribution pattern of carbides, it can be divided into two types: flake pearlite and spherical pearlite.

What is the difference between ferrite and austenite?

Austenite and ferrite. Austenite was originally used to describe an iron-carbon alloy, in which the iron was in the face-centred-cubic (gamma-iron) form. It is now a term used for all iron alloys with a basis of gamma-iron. Austenite in iron-carbon alloys is generally only evident above 723°C, and below 1500°C, depending on carbon content.

What kind of steel is made of ferrite?

Figure 1 shows the appearance of ferrite grains in a carbon steel used for motor laminations. There are also ferritic stainless steels, which contain high chromium contents and very little carbon. Ferrite is a very soft, ductile phase, although it loses its toughness below some critical temperature.

How is pearlite formed from ferrite and cementite?

Pearlite. It is usually a lamellar (alternate plate) combination of ferrite and cementite (Fe 3 C). It is formed by eutectoid decomposition of austenite upon cooling by diffusion of C atoms, when ferrite and cementite grow contiguously, C precipitating as Fe 3 C between laths of ferrite at the advancing interface,…