Rationale

In 2019, Task Group E08.07.05 on Fracture Toughness conducted a computational round-robin on ASTM E1820- Standard Test Method for Measurement of Fracture Toughness to determine the ‘correct’ results for a set of eight standard data sets for E1820 (E1820-DS2 – E1820-DS9). The current version of the standard at that time was E1820-18ae1. Since then, there have been revisions to Section A9 that can impact the calculation of JQ. In particular, the convergence criterion for determining the intersection of the power law to the 0.2mm offset line was changed from 2% to 0.1% and Annex A9 permits any solver to be used to compute the intersection. This may result in a change to the reported JQ value depending upon the actual convergence criterion and solver employed when calculating the results. A computational round robin was conducted to determine the expected values for the results of the standard data sets based on Annex A9 of E1820-24. In addition to the four participants in the original round robin, four new participants submitted results to be used to determine the expected values based on the latest version of E1820. As a consequence of doubling the number of results used to determine the expected values, the allowable tolerances for the various parameters increased slightly. The expected values for the data sets were taken as the average of all of the submitted results and the tolerance on the different parameters was set between 2 – 2.5X the standard deviation of the results for the parameters. The changes to the expected values and tolerances are small in an absolute sense and are believed to better reflect reasonable variations in the parameters as a result of doubling the sample size of calculations used to establish the expected results.