# What is interlamellar spacing of pearlite?

## What is interlamellar spacing of pearlite?

The interlamellar spacing of pearlite is a very important microstructural parameter for steels containing pearlite, and becomes more important as the pearlite content increases towards a fully pearlitic microstructure.

What is the microstructure of pearlite?

Pearlite is essentially a composite microstructure consisting of cementite layers (which are hard and brittle) sandwiched between ferrite layers (which are soft and ductile).

Why does pearlite form a lamellar structure?

During slow cooling pearlite forms by a eutectoid reaction as austenite is cooled below 727°C (the eutectoid temperature). An intimate mixture with ferrite, the other product of austenite, forms a lamellar structure called pearlite.

### What are the characteristics of pearlite?

Pearlite can be hard and strong but is not particularly tough. It can be wear-resistant because of a strong lamellar network of ferrite and cementite. Examples of applications include cutting tools, high strength wires, knives, chisels, and nails.

What does Interlamellar mean?

Between lammellæ or laminæ; as, interlamellar spaces.

Is pearlite and cementite harder?

leads to the formation of pearlite, which in a microscope can be seen to consist of alternate laths of alpha-ferrite and cementite. 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.

## Why is pearlite called pearlite?

The eutectoid structure in iron has a special name: it is called pearlite (because it has a pearly look). The schematic and micrograph below show pearlite. It is important to note that pearlite is not a phase, but a mixture of two phases: ferrite and cementite.

Why is the interlamellar spacing of pearlite so important?

The interlamellar spacing of pearlite is a very important microstructural parameter for steels containing pearlite, and becomes more important as the pearlite content increases towards a fully pearlitic microstructure.

Which is the best interlamellar spacing for wire?

Interlamellar spacing data can be correlated to the heat treatment variables and to mechanical properties, such as strength, hardness and toughness. For wire drawing, near eutectoid grades exhibit better drawability, strength and ductility when isothermally transformed to produce the finest interlamellar spacing.

### Which is the best grid for pearlite spacing?

The circular grid is ideal as it insures that a random spacing is measured. If the amount of pearlite is <50% of the field area the magnification must be raised to ensure that the circle covers only pearlite.

How is the interlamellar spacing of cementite determined?

Perhaps the most common approach to measuring interlamellar spacing is to draw lines perpendicular to the cementite lamellae in each colony and then determine the apparent spacing based upon the number of lamellae intercepted divided by the true line length to give a directed spacing, σd.