Image icon  Ni-hard iron

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Description: 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.
Keywords: alloy • cast iron • dendrite • iron • metal • Ni-hard iron • nickel
Categories: Science approaches > Microstructure
Materials > Metals & alloys > Cast irons
Processes > Shaping > Casting
Testing, analysis & experimentation > Metallography
Scale > Micro
Created by: Prof T W Clyne, Department of Materials Science and Metallurgy, University of Cambridge
DoITPoMS, University of Cambridge
Published by: DoITPoMS, University of Cambridge
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Date created: 25 October 2001
Date added: 21 August 2009
Resource ID: 1140