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Acceptance of new batches of 9310 steel for the Charpy Machine Verification Program



May Ling Martin, Enrico Lucon


During FY2021, one of the NIST Charpy Contractors returned some 9310 steel blanks (rough-machined, oversized, unnotched specimens) that presented visible black surface defects (similar to gouges, some with raised strips of steel). On a couple of these blanks, optical microscopy and chemical analysis by Electron Dispersive Spectroscopy were conducted in order to establish the nature of such defects. It was concluded that they correspond to segregation zones formed during steel-making, which the final processing failed to remove. These surface layers (< 1 mm) are brittle in nature and are likely to be removed during sample machining.
NIST Interagency/Internal Report (NISTIR) - 8435
Report Number


9310 steel, Electron Dispersive Spectroscopy, segregation zones, surface defects.


Martin, M. and Lucon, E. (2001), Acceptance of new batches of 9310 steel for the Charpy Machine Verification Program, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 12, 2024)
Created January 1, 2001, Updated November 29, 2022