Charpy衝擊試驗是自20世紀初以來在全球範圍內使用的一種技術，用於表徵金屬的缺口韌性，從而適用於從船體和鐵軌到核反應堆壓力容器的各種應用。自1989年以來，NIST一直向國際社會提供經過認證的參考樣本，可用於間接驗證夏比機符合ASTM E23標準。截至2012年版本，ASTM E23僅覆蓋Charpy衝擊器，衝擊半徑等於8毫米;撞擊器是撞擊和破裂試樣的鐘擺的一部分。 NIST提供的Charpy SRM（2092,2093,2096,2097,2098）因此只能用於驗證配備8mm衝擊器的機器。在2016年對ASTM E23進行了修訂後，其中包括裝備有2mm撞擊器（擊球邊緣半徑= 2mm）的機器，這些機器已經被ISO 148等其他完善的標準所涵蓋，NIST決定認證並提供夏比參考用於間接驗證帶有2mm撞擊器的機器的樣本。 SRM 2197（低能量）和SRM 2198（高能量）現在可以以自我驗證標本的形式提供給客戶。與現有的SRM 2093和SRM 2097（與8mm衝擊器一起使用）類似，購買SRM 2197和SRM 2198的客戶將獲得具有相應認證值的證書和擴展吸收能量的不確定性，並且可以根據其自身確定測試結果，他們的機器是否符合ASTM E23。破損的樣本不會退回給NIST，也不會核發正式的驗證書。與用於8mm衝擊器的SRM（必須在-40°C下測試）不同，SRM 2197和SRM 2198必須在室溫（21°C±1°C）下進行測試。

Charpy impact testing is a technique used worldwide since the early 1900s for characterizing the notch toughness of metals, and thereby their suitability for applications ranging from ship hulls and railroad tracks to nuclear reactor pressure vessels. Since 1989, NIST has been providing the international community with certified reference specimens, which can be used to indirectly verify a Charpy machine for compliance with the ASTM E23 standard. Up to its 2012 version, ASTM E23 only covered Charpy strikers with a radius of striking edge equal to 8 mm; the striker is the part of the pendulum that impacts and fractures the specimens. The Charpy SRMs supplied by NIST (2092, 2093, 2096, 2097, 2098) could therefore only be used to verify a machine equipped with an 8-mm striker. After ASTM E23 was revised in 2016 to include machines equipped with 2-mm strikers (radius of the striking edge = 2 mm), which were already covered by other well-established standards like ISO 148, NIST decided to certify and make available Charpy reference specimens to be used for the indirect verification of machines with 2-mm strikers. SRM 2197 (low energy) and SRM 2198 (high energy) are now available to customers in the form of Self-Verification specimens. Similar to the existing SRM 2093 and SRM 2097 (used with 8-mm strikers), customers who purchase SRM 2197 and SRM 2198 receive certificates with the corresponding certified values and expanded uncertainties of absorbed energy, and can autonomously establish, on the basis of their test results, whether their machines are in compliance with ASTM E23. Broken specimens are not returned to NIST, and no official Verification Letter is issued. Unlike SRMs for 8-mm strikers, which must be tested at -40 °C, SRM 2197 and SRM 2198 must be tested at room temperature (21 °C ± 1 °C).