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Inclusion Ratings: Past, Present, and Future Pages: 14 Published: Jan 1998
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View License Agreement Source: STP1327-EB 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 ASTM International is a member of CrossRef. | ||