Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 265

Full Record for Micrograph 265

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Micrograph no
265
Brief description
Fe, C 0.8 (wt%) steel, eutectoid transformation, spheroidised
Keywords
alloy Link to MATTER Glossary entry for alloy, carbon, iron, metal, normalising Link to MATTER Glossary entry for normalising, spheroidised, steel Link to MATTER Glossary entry for steel
Categories
Metal or alloy
System
Fe-C-X   Link to phase diagram
Composition
Fe, C 0.8 (wt%)
Standard codes
Reaction
Processing
Spheroidised
Applications
Sample preparation
Nital
Technique
Reflected light microscopy
Length bar
400 μm
Further information
This steel is of the eutectoid composition. Once the temperature is lowered below the eutectoid temperature, the austenite phase tends to undergo a eutectoid transformation (g to a + Fe3C). The resultant microstructure, known as pearlite, comprises alternate lamellae of cementite and ferrite. Subsequent to casting, the alloy was normalised (annealed) just below the eutectoid temperature, in order to induce the carbides to take a spherical appearance, which results in the steel becoming softer and more ductile. This is known as spheroidisation. The changes to the morphology of the cementite cannot be seen clearly in this micrograph, but they are discernible at higher magnification (see micrographs 266 and 267).
Contributor
Dr R F Cochrane
Organisation
Department of Materials, University of Leeds
Date
04/09/02
Licence for re-use
Attribution-NonCommercial-ShareAlike 4.0 International
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