On the Possibility of Adding a Repeatability Requirement for the Indirect Verification of Charpy Machines in ASTM E23

Published

March 27, 2025

Author(s)

Enrico Lucon

Abstract

Since 1989, the NIST Charpy Machine Verification Program in Boulder, Colorado has been indirectly verifying Charpy machines around the world according to ASTM E23, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, and ISO 148-2. Most of the indirect verifications results have been logged in a database, which at the end of May 2024 included 77105 records, each one corresponding to 4-5 absorbed energy values at one of three energy levels (low, high, and super-high). Based on the analysis of this database, the acceptability criteria of ASTM E23, exclusively based on bias, have been compared with those of ISO 148-2, which also include repeatability. The objective of this study is to support the proposal of revising ASTM E23 by introducing repeatability requirements in addition to the existing bias criteria. Four proposals have been considered and assessed, leading to the selection of a set of repeatability limits (larger of 4 J and 15 % of certified absorbed energy) that only moderately increases the severity of the standard, but most importantly prevents deeming acceptable machines that satisfy ASTM bias but fail ISO repeatability (approximately 1/6 of all the machines verified by NIST since 1990).

Citation

Materials Performance and Characterization

Volume

14

Issue

1

Pub Type

Journals

Download Paper

https://doi.org/10.1520/MPC20240077

Local Download

Keywords

ASTM E23, bias, indirect verification, ISO 148-2, NIST Charpy database, NIST Charpy Program, repeatability

Citation

Lucon, E. (2025), On the Possibility of Adding a Repeatability Requirement for the Indirect Verification of Charpy Machines in ASTM E23, Materials Performance and Characterization, [online], https://doi.org/10.1520/MPC20240077, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958877 (Accessed April 24, 2025)