'Bainite' is a mostly
metallic substance that exists in
steel after certain
heat treatments. First described by
Davenport E. S. and
Edgar Bain, it forms when
austenite (a solution of
carbon in
iron) is rapidly cooled past a critical temperature of 723°C (about 1333°F).
A fine non-lamellar structure, bainite commonly consists of
ferrite and
cementite. It is similar in constitution to
pearlite, but with the ferrite forming by a displacive mechanism similar to
martensite formation, usually followed by precipitation of carbides from the supersaturated ferrite or austenite.
When formed during continuously cooling, the cooling rate to form bainite is higher than that required to form pearlite, but lower than that to form martensite, in steel of the same composition.
Bainite is generally stronger and more
ductile than pearlite.
External links
★
Online textbook devoted to bainite, from
Cambridge University Press and the
Institute of Materials
★
The Alloying Elements in Steel, by Edgar C. Bain