Journal Published Online: 31 January 2019
Volume 47, Issue 2

Influence of Shear Lip Symmetry on the Fracture Behavior of Charpy Specimens



An investigation was conducted at the National Institute of Standards and Technology (NIST) on the influence of shear lip symmetry on the fracture behavior (absorbed energy and data scatter) of Charpy specimens at different energy levels, corresponding to NIST low-energy, high-energy, and super-high-energy certified verification specimens. Whenever both shear lips are on the same tested specimen half (symmetrical fracture), absorbed energy tends to be lower than when each specimen half includes one shear lip (asymmetrical fracture). Fracture type does not have a significant effect on impact toughness or variability at low- or high-energy levels, but its influence becomes significant above 200 J. Specifically, super-high-energy specimen lots do not fulfill the NIST requirement (sample size < 5.0) when both fracture types are combined, whereas they may become acceptable if only symmetrical or asymmetrical fractures are considered. This tendency is particularly clear for the 9310 (3-nickel) steel, which is currently under consideration for the reinstatement of super-high-energy specimens in the NIST Standard Reference Materials catalog. The most effective method for preventing the formation of shear lips, and therefore avoiding this type of bimodal behavior, is to side-groove the Charpy specimens for a total thickness reduction of 10 %.

Author Information

Lucon, Enrico
Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO, USA
Pages: 18
Price: $25.00
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Stock #: JTE20180403
ISSN: 0090-3973
DOI: 10.1520/JTE20180403