Journal Published Online: 16 May 2022
Volume 50, Issue 4

On the Question of How to Analyze and Apply Charpy Pendulum Impact Test Results Correctly - Shortcomings in Corresponding Procedures and Standards

CODEN: JTEVAB

Abstract

This paper is focused on the approximation of absorbed Charpy impact energy-temperature curves (KV-T) and the management of sub-size test piece results in Charpy pendulum impact tests. Both subjects are frequently underestimated but may have a strong impact on the assessment of product quality and structural integrity. The status of related test standards, product standards, structural integrity assessment procedures and corresponding research is reviewed. It is concluded that the state of regulation is partly insufficient and wrong. There is a wide gap between the state of knowledge in the field of materials testing and the requirements of product standards and structural integrity assessment procedures. The present paper aims at boosting and supporting the necessary discussion among the parties involved to raise the level of technical safety. Correspondingly, a large experimental database was created by Charpy impact testing of popular modern structural Steels with nominal yield strength from 235 MPa to 960 MPa. KV-T data were generated using test pieces with thicknesses between 2.5 mm and 10 mm. Different strategies for KV-T curve fitting, definition of transition temperatures, as well as upper and lower shelf energy levels were followed, and different scaling procedures were applied to the sub-size test piece results. The results show that proportional scaling of sub-size to full-size test piece results in terms of KV should be disallowed because it is a wrong approach. Regulations still incorporating such procedures should be revised as soon as possible. Existing nonproportional scaling and conversion procedures were applied. The results obtained illustrate that neither an overall nor consistent conservatism nor an adequate conservatism level can be achieved. In summary, the standardizing bodies should enforce the discussion to revise relevant test standards considering more precise specifications on Charpy data fitting. Furthermore, proposals are made for an improved management of sub-size test piece results.

Author Information

Baer, Wolfram
Federal Institute for Materials Research and Testing (BAM), Berlin, Germany
Wossidlo, Peter
Federal Institute for Materials Research and Testing (BAM), Berlin, Germany
Abbasi, Behboud
Federal Institute for Materials Research and Testing (BAM), Berlin, Germany
Pages: 26
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Stock #: JTE20210781
ISSN: 0090-3973
DOI: 10.1520/JTE20210781