Steels: pearlite. Lecture 8 of 12
Channel: bhadeshia123
Date: 01/10/2020

Pearlite is probably the most familiar microstructural feature in the whole 
science of metallography. It was discovered by Sorby some
130 years ago, who correctly assumed it to be a lamellar mixture of iron and 
iron carbide. Pearlite is an extremely common constituent of a wide variety of steels, where it provides a substantial contribution to strength, so it is 
not surprising that this phase has received intensive study. Lamellar 
eutectoid  structures of this type are widespread in metallurgy, and 
frequently, pearlite is used as a generic term to describe them. These 
structures have much in common with the cellular precipitation reactions. 
Both types of reaction occur by nucleation and growth  and rely 
on the cooperative growth of phases during diffusional growth. Pearlite nuclei occur on austenite grain boundaries, but it is 
clear that they can also be associated with both pro-eutectoid ferrite and 
cementite. In commercial steels, pearlite nodules can nucleate on 
inclusions.


Associated teaching materials can be found on:
http://www.phase-trans.msm.cam.ac.uk/teaching.html
H. K. D. H. Bhadeshia