Volume 34, Issue 6 (November 2006)
Round Robin Test on Normalization Method under Static Loading Condition
In 2001, the normalization method was approved as ASTM Method E 1820-01  for use in high loading rate J-R tests. Prior to its approval, High Rate Round Robin was conducted under the coordination of ASTM Subcommittee E08.08.02 for the verification of accuracy and reproducibility of the method. However, the results of the normalization method cannot be verified against those of other well-established methods because no other method is available in the high loading rate condition. In this round robin test, J-R curves were measured under static loading conditions for A106Gr. C nuclear piping steel by the normalization method so that results can be compared with those obtained simultaneously by the unloading compliance method. The deviation of JIc by normalization and differences of JIc values from those of the unloading compliance method were quantified. The normalization method showed JIc deviation up to 60 % when tested with initial a/W=0.5. In order to seek ways to reduce the deviation, both offset method and tangent method were tried for normalization analysis, but with limited improvement. These partially modified normalization methods of the offset method and tangent method decreases the deviation of JIc, but increases the difference from those of the unloading compliance method. More fundamental approaches are warranted for adequate improvement.