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Using "Off-the-Shelf" AISI 4340 Steel for the Production of NIST Reference Charpy Specimens
Published
Author(s)
Enrico Lucon, Allen Eckhardt, Raymond Santoyo
Abstract
We investigated the suitability of using readily available ("off-the-shelf"), as opposite to made-to-order, AISI 4340 steel for the production of NIST reference Charpy specimens of low- and high-energy level. This study was preceded by technical discussions inside and outside NIST, which lead to the streamlining and simplification of the technical specifications for the procurement of 4340 steel, as well as 9310 steel (used for the production of super-high-energy reference specimens). Charpy tests were performed on the three reference machines in Boulder, on trial lots of 75 specimens, heat treated and machined according to the same procedures used by our current Vendors for reference specimens. Four of the six "off-the-shelf" 4340 steel heats were found immediately acceptable according to the NIST criterion (sample size ≤ 5.0). The remaining two heats yielded sample sizes between 5 and 6, and after re-tempering and machining the few remaining blanks, the corresponding Charpy tests provided relatively low sample sizes. The outcome of this investigation supports the validity of our revised steel specifications and the acceptability of "off-the-shelf" 4340 steel batches for the Charpy Machine Verification Program.
Lucon, E.
, Eckhardt, A.
and Santoyo, R.
(2025),
Using "Off-the-Shelf" AISI 4340 Steel for the Production of NIST Reference Charpy Specimens, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.IR.8556, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959266
(Accessed October 14, 2025)