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Certified KLST Miniaturized Charpy Specimens for the Indirect Verification of Small-Scale Impact Machines



Enrico Lucon, Christopher N. McCowan, Raymond L. Santoyo, Jolene D. Splett


Small specimen test techniques are becoming ever more popular as the need increases to characterize mechanical properties by use of the smallest possible amount of material, due to various restrictions on material availability, irradiation, testing space, and other factors. NIST recently qualified reference miniaturized Charpy V-notch (MCVN) specimens for the indirect verification of small-scale impact testing machines (with capacity in the range 15 J to 50 J and impact velocity around 3.8 m/s). The same materials used for NIST standard verification specimens were evaluated at three energy levels (low, high and super-high). The miniaturized specimen type investigated is denominated KLST (from the German Kleinstprobe, or “small specimen”). In the first phase of the qualification activity, several instrumented impact tests on miniaturized KLST specimens of low, high and super high energy were performed and analyzed at NIST. In this part of the study, which was published elsewhere, the variability of MCVN data was compared to that of full-size Charpy data from the same lot of specimens. Additional aspects were also investigated, such as the influence of shear lip symmetry and specimen full or partial fracture on absorbed energy, and the correlation between miniaturized and full-size Charpy data. In the second phase of the qualification activity, certified values of absorbed energy and maximum force were established for each energy level by means of an International Round Robin, which involved nine highly qualified laboratories. The results of this Round Robin, and the outcome of the statistical analyses performed in accordance with ASTM E691-13 and ISO 5725-2:1994, are presented in this paper. Complete details are provided in the NIST Certification Report SP 260-180, which accompanies the certified KLST.
Proceedings Title
Conference Dates
January 29-31, 2014
Conference Location
Houston, TX
Conference Title
Small Specimen Test Techniques - 6th ASTM Symposium


Small specimen test techniques, miniaturized Charpy specimens, small-scale impact machines, KLST, instrumented impact tests, international Round-Robin, statistical analyses


Lucon, E. , McCowan, C. , Santoyo, R. and Splett, J. (2015), Certified KLST Miniaturized Charpy Specimens for the Indirect Verification of Small-Scale Impact Machines, ASTM STP 1576, Houston, TX (Accessed May 19, 2024)


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Created April 28, 2015, Updated February 19, 2017