NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PUBLICATIONS

Dimensional Inspection of Charpy Indirect Verification Specimens By Means of a Digital Optical Comparator

Published

Author(s)

Enrico Lucon, Raymond L. Santoyo, Allen Eckhardt

Abstract

The Charpy reference specimens produced by NIST for the indirect verification of Charpy machines in accordance with ASTM E23 and ISO 148-1 must satisfy strict dimensional requirements, with tolerances that are in most cases tighter than those prescribed by the standards. In the past, Charpy specimens to be certified were dimensionally inspected by means of an optical comparator (shadowgraph), which has been replaced in 2019 by a digital optical comparator manufactured by Keyence, which provides enhanced measurement accuracy. This report provides step-by-step operating instructions for the dimensional inspection of Charpy certified reference specimens using the digital measurement system, as well as details about its annual recertification, and the NIST dimensional criteria for lot acceptance. Measurements conducted at NIST on five Charpy specimens using the digital comparator were found in excellent agreement with data provided by participants in an ASTM Interlaboratory Study (ILS 1151), demonstrating the accuracy and reliability of the Charpy measurement system currently used at NIST.
Citation
NIST Interagency/Internal Report (NISTIR) - 8507
Report Number
8507
NIST Pub Series
NIST Interagency/Internal Report (NISTIR)
Pub Type
NIST Pubs

Download Paper

Local Download

Keywords

ASTM E23, Charpy reference specimens, digital optical comparator, dimensional requirements, indirect verification, Interlaboratory Study (ILS), ISO 148-1.
Materials

Citation

Lucon, E. , Santoyo, R. and Eckhardt, A. (2024), Dimensional Inspection of Charpy Indirect Verification Specimens By Means of a Digital Optical Comparator, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957200 (Accessed October 8, 2025)

Issues

If you have any questions about this publication or are having problems accessing it, please contact [email protected].

Created February 26, 2024
Was this page helpful?