On the Possibility of Extracting Reference Charpy Specimens from 4340 Steel Round Bars with D >= 1 in.

Published

September 16, 2025

Author(s)

Enrico Lucon

Abstract

We have investigated the possibility of extracting low- and high-energy reference Charpy specimens, to be certified for the indirect verification of impact machines in accordance with ASTM E23, from round bars of 4340 steel with larger diameters than the ones currently used, i.e., D >= 1" (25.4 mm). Larger round bars would allow extracting specimens from adjacent locations within the bar cross-section, rather than only in the center. The influence of sampling location on Charpy absorbed energy was found to be statistically significant in most investigated scenarios. However, the Charpy results obtained in every possible scenario all satisfy the NIST acceptability criterion based on sample size, and therefore indicate that the use of larger bars and side-by-side sampling is a viable option, when the currently preferred diameter (5/8") is unavailable. Between 1" and 1 ¼" diameter bars, the former show slightly lower data scatter than the former, but also correspond to higher estimated cost and material waste per specimen.

Citation

NIST Interagency/Internal Report (NISTIR) - 8590

Report Number

8590

NIST Pub Series

NIST Interagency/Internal Report (NISTIR)

Pub Type

NIST Pubs

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Keywords

4340 steel, ASTM E23, material waste, reference Charpy specimens, round bars, sample size, sampling location

Citation

Lucon, E. (2025), On the Possibility of Extracting Reference Charpy Specimens from 4340 Steel Round Bars with D >= 1 in., NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960711 (Accessed September 17, 2025)