STP1327: Inclusion Ratings: Past, Present, and Future

    Vander Voort, GF
    Director, Buehler Ltd., Lake Bluff, IL

    Pages: 14    Published: Jan 1998


    Abstract

    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.

    Keywords:

    automatic image analysis, bearing steels, nonmetallic inclusions, oxides, sulfides, stereology


    Paper ID: STP12117S

    Committee/Subcommittee: A01.28

    DOI: 10.1520/STP12117S


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