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Full Record for Micrograph 72

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Micrograph no
72
Brief description
Ni-hard iron
Keywords
alloy Link to MATTER Glossary entry for alloy, cast iron Link to MATTER Glossary entry for cast iron, dendrite Link to MATTER Glossary entry for dendrite, iron, metal, Ni-hard iron Link to MATTER Glossary entry for Ni-hard iron, nickel
Categories
Metal or alloy
System
Fe-C-X   Link to phase diagram
Composition
Fe, C 2.8, Ni 4.5, Mn 1.2, Cr 0.75, Si 0.5, P 0.3, Mo 0.25, S 0.1 (wt% typical) (Ni-hard iron)
Standard codes
Reaction
Processing
Applications
Sample preparation
Technique
Reflected light microscopy
Length bar
400 μm
Further information
This is a Ni-hard iron, one of the first cast irons to be developed. These white irons contain Ni to ensure that the austenite transforms to martensite following heating and chromium to increase the hardness of the eutectic carbide.

Ni-hard irons are normally stress relieved at 200-300 °C for approximately four hours to relieve the martensitic transformation stresses and to promote the transformation of retained austenite. The structure consists of proeutectic austenite dendrites containing martensitic needles with interdendritic austenite-martensite/carbide eutectic.
Contributor
Prof T W Clyne
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
25/10/01
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales
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