Page 6 - Heat Treatment of Steels (การอบ-ชุบ เหล็กกล้า)

What happens when a steel is heated or cooled

under nonequilibrium condition?

 On heating, phase change as in Phase Diagram.

 On rapid Cooling, C atom in -FCC are trapped, resulting

in a (Body centered tetragonal) structure which is called

“Martensite”

Slow cooling
Equilibrium

Rapid

cooling BCC

-FCC

T> A c3

BCT (up to 60 HRC with 0.6%C)
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