Micrograph 241 and full record
- Micrograph no
- 241
- Brief description
- Fe, C 0.3 (wt%) steel, spheroidised carbide
- Keywords
- alloy , carbon, hypoeutectoid , iron, metal, pearlite , steel
- Categories
- Metal or alloy
- System
- Fe-C-X
- Composition
- Fe, C 0.3 (wt%)
- Standard codes
- Reaction
- Processing
- Spheroidised
- Applications
- Sample preparation
- Nital
- Technique
- Reflected light microscopy
- Length bar
- 400 μm
- Further information
- A hypoeutectoid alloy (composition less than eutectoid). The first phase formed upon cooling from the austenite phase field is proeutectoid ferrite. Due to the lower solubility of carbon in ferrite, carbon is partitioned into the remaining austenite. At the eutectic point the remaining carbon-enriched austenite transforms to pearlite (a mixture of ferrite and cementite), which is the darker region of the micrograph. The proportion of pearlite is dependent upon the overall composition.
Subsequent to casting the sample was annealed for a long period just below the transformation range. This induces the cementite to take on a spherical appearance. This results in a softer and more ductile alloy. This process is known as spheroidisation. The changes to the morphology of the cementite cannot be seen clearly in this micrograph, but they are more apparent at higher magnification (see micrograph 242). - 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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