SYMPOSIA PAPER Published: 01 January 1998

Inclusion Ratings: Past, Present, and Future


Chart-based techniques, such as ASTM E 45, have been used to rate inclusion types and content for more than half a century. Chart ratings are subject to considerable error, reproducibility among raters is poor, and they lack precision for today's steels with very low inclusion contents. Image analysis procedures, using ASTM E 1122, where the rating system has been modified to generate improved JK-chart ratings, are now being used widely. A new, alternate approach using stereological relationships for inclusion measurements is given by ASTM E 1245. In this method, the inclusions are separated by type (oxide vs. sulfide usually) and the volume fraction, number per unit area, average length, average area, and spacing are determined. E 1245 is easy to do by image analysis and is fast. In this paper, heats of 52100 bearing steel, made by different technologies, were rated using the current E 45/E 1122 method and by the method of the future, E 1245. The greater merit of the E 1245 method was demonstrated statistically by comparing the test results for the steels made by the different procedures.

Author Information

Vander Voort, GF
Buehler Ltd., Lake Bluff, IL, USA
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Developed by Committee: A01
Pages: 13–26
DOI: 10.1520/STP12117S
ISBN-EB: 978-0-8031-5381-3
ISBN-13: 978-0-8031-2421-9