What is perlite structure?
Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite (87.5 wt%) and cementite (12.5 wt%) that occurs in some steels and cast irons. Pearlite is a microstructure occurring in many common grades of steels.
What is pearlite and how does it form?
How is pearlite formed ? Pearlite is formed during sufficiently slow cooling in an iron-carbon system at the eutectoid point in the Fe-C phase diagram (723 °C, eutectoid temperature). Pearlite is known for being tough and, when highly deformed, extremely strong.
Why is it called pearlite?
Pearlite is the name given to the eutectoid mixture of steel – a lamellar mixture of ferrite (alpha) and cementite. Pearlite is so called because it looks like mother of pearl when viewed under a microscope.
What is perlite in metallurgy?
Pearlite is a mixture of ferrite and cementite forming distinct layers or bands in slowly cooled carbon steels. Pearlite is an iron alloy that contains around 88% ferrite and 12% cementite. Pearlite is known for being tough and it is used in a variety of applications, including: Cutting tools. High-strength wires.
Is cementite FCC or BCC?
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.
How is fine pearlite formed?
A simple heat treatment obtained by austenitizing and air cooling to produce a fine pearlite structure. Pearlite. A two-phase lamellar micro-constituent, containing ferrite and cementite, that forms in steels that are cooled in a normal fashion or are isothermally transformed at relatively high temperatures.
How is pearlite formed?
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 3C between laths of ferrite at the advancing interface, leaving parallel laths of Fe and Fe 3C which is pearlite. …
Is perlite bad for your lungs?
Perlite dust can be extremely fine and being light, it remains airborne for much longer periods of time than normal dust. Because it can be inhaled easily, it is very dangerous. Inhaling perlite dust is no different to inhaling smoke, cement dust, or any other dangerous dust.
Should I wear a mask when using perlite?
Perlite is volcanic glass. A dust mask to protect your lungs is imperative. And I recommend an inexpensive pair of safety glasses to protect your eyes from those tiny particles of volcanic glass that fill the air as you work with it.
What kind of structure is a pearlite made of?
Metallurgy. a microscopic lamellar structure found in iron or steel, composed of alternating layers of ferrite and cementite. Petrography. perlite.
Why are ferrite and cementite called pearlite?
Under high magnification the ferrite and cementite can be seen to be arranged in alternate laminations or plates. When seen in the microscope the surface has appearance like mother of pearl, hence the name pearlite.
How is pearlite related to the mother of Pearl?
It is named for its resemblance to mother of pearl. If steel (austenite) with a eutectoid composition of approximately 0.77% C is slowly cooled below 727 °C, the ferrite and cementite phase separate almost simultaneously to produce a microstructure with distinctive platelets. This distinctive microstructure of steel is called pearlite.
Which is the continuous phase of pearlite steel?
This constituent-pearlite-consists of alternate plates of cementite and ferrite, with ferrite the continuous phase as illustrated in Fig. 3.19 (a microstructure of furnace cooled eutectoid steel). Pearlite is not a phase, but a mixture of two phases, viz., cementite and ferrite.