Installing, Maintaining, and Verifying Your Charpy Impact Machine. NIST Recommended Practice Guide

摘要

The quality of the data developed by pendulum impact machines depends on how well the machines are installed, maintained, and verified. This is the reason that ASTM Standard E 23 Standard Test Methods for Notched Bar Impact Testing of Metallic Materials specifies annual direct and indirect verification tests. Each year, NIST provides reference specimens for indirect verification of over 1000 machines around the world. From evaluation of the absorbed energies and the fractured specimens, the authors attempt to deduce the origin of energies that are outside the ranges permitted by Standard E 23, and report these observations back to the machine owners. This recommended practice summarizes the bases for these observations, and hopefully will allow machines to be maintained at higher levels of accuracy. In addition, the authors provide details of the NIST verification program procedures and the production of the specimens.