Characterization of multicomponent scales by electron back scattered diffraction (EBSD)
Exposure of metals and alloys to high temperatures leads to the formation of oxide scales. Characterizing the nature of the scale is of considerable importance to the steel manufacturers, who are under continual pressure to improve surface finish. Scale properties are also of interest because of the effect on friction and heat transfer during hot working operations, and the resultant wear of tooling or work rolls. Oxidation of pure iron is well documented and has lead to the classical three layer scale characterization. Hot working operations break up the classical three layer scale and make characterization of the individual components of the scale difficult. Identification of the individual components simply by their layer position is no longer reliable since the layers have been disrupted by the hot working process. Scale microstructures become further complicated on cooling as the wuestite decomposes to magnetite at temperatures below 570 C. The resultant scale microstructures are therefore complex on a sub-micron scale. These secondary and tertiary scales must be removed before subsequent processing, such as cold rolling or wire drawing and the mechanical properties of the scale layers are important factors when considering descalability. For example, hematite is much harder than magnetite and wuestite, thus magnetite scales are more brittle and therefore easier to remove than scales containing wuestite.with this in mind it is necessary to develop a reliable technique for the characterization of these scales and their microstructures with respect to developing an ideal scale for easy removal, without sacrificing the mechanical properties of the product. Furthermore a reliable method of characterizing the scale development along the rolling mill would be useful in charting the scale growth and re-growth behavior between passes and may lead to the development of an ideal rolling schedule for the formation of an easily removed scale. This paper discusses the characterization of these scales by electron back scattered diffraction.
- Research Organization:
- Sheffield Univ. (GB)
- OSTI ID:
- 20013343
- Journal Information:
- Scripta Materialia, Vol. 42, Issue 3; Other Information: PBD: Jan 2000; ISSN 1359-6462
- Country of Publication:
- United States
- Language:
- English
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