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The objective of the project is to develop the necessary methodology for the qualitative description and the quantitative determination of phases in multiphase steel grades. A standard and simple procedure for the identification and quantification of all constituents in multi-phase steels needed to be defined. The focus was on etching methods for optical microscopy, easily applicable for routine control in the quality lab. This research has demonstrated with round robin tests that it is almost impossible to define such a standard procedure. The etching methods were however optimised and a 'guideline' procedure based on different etching methods was defined. For the identification of fine microstructures complementary investigations with high resolution techniques are necessary. During the project methods were identified which allow better quantification of the micro-structure of multi-phase steels. Quantification of martensite and austenite is possible via OM in combination with (different) etching techniques. Only a very rough estimation of the bainitic fraction can be obtained via OM, because of the difficulty to distinguish between polygonal and bainitic ferrite. Other techniques such as EBSD or electron diffraction in TEM still need to be optimised. With X-ray diffraction reliable results can be obtained for the austenite in a plane and magnetic measurements give bulk values for the fraction. X-ray diffraction measurements can also give a fast and accurate estimation of the average C-content in austenite. PEELS is a more direct method and allows local measurements of C in the different phases.

Additional information

Authors: LEUNIS E, Arcelor Research Industry, Zelzate (BE);HANLON D, Corus, Ijmuiden (NL);RIJKENBERG A, Corus, Ijmuiden (NL);SCOTT C, Arcelor Research SA, Maizières-lès-Metz (FR);DRILLET J, Arcelor Research SA, Maizières-lès-Metz (FR);HACKL R, Voestalpine Stahl, Linz (AT)
Bibliographic Reference: EUR 22387 EN (2006), 123 pp. Euro: 25
Availability: Katalogue Number: KI-NA-22387-EN-S The paper version can be ordered online and the PDF version downloaded at:
ISBN: ISBN: 92-79-02658-5
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