SEDL / STP / STP987-EB / STP26238S

Measurement of Extremely Low Inclusion Contents by Image Analysis

Vander Voort, GF
Supervisor, Metal Physics Research and Development, Carpenter Technology Corporation, Research and Development Center, Reading, PA

Pages: 24    Published: Jan 1988

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Abstract

Image analysis measurements using a stereological approach have been performed on the inclusions in VIM/EBR, VIM/VAR, and VIM/ESR material from the same parent VIM heat of M-50 bearing steel. Tests made on billet samples produced excessively high, inaccurate results due to very fine microshrinkage cavities associated with the carbide due to insufficient hot reduction. Subsequent tests on bar specimens revealed a closer correlation with the calculated volume fractions based on sulfur and oxygen chemical analysis. However, the measured area fractions were consistently lower than the calculated values. Details of the metallographic preparation problems are provided.