Rationale

Before ASTM E1820 was first published in 1996, two ASTM standards existed for elastic-plastic fracture toughness testing: ASTM E813 (withdrawn in 1997), which covered the determination of critical fracture toughness values (JIc, ?Ic), and ASTM E1152 (withdrawn in 1997), which addressed the establishment of J-R crack resistance curves. E813 allowed two approaches for assessing critical fracture toughness: multi-specimen and single-specimen (primarily elastic compliance, but other techniques for measuring crack extension were allowed). On the other hand, E1152 only allowed the use of single-specimen techniques (elastic compliance or equivalent) for establishing J-R curves. When the first version of E1820 was issued in 1996, the distinction between multi- and single-specimen techniques was retained, but the two approaches were renamed “basic procedure” and “resistance curve procedure” respectively. The former could only be used for JIc and ?Ic, while the latter could also be used for J-R and ?-R curves. This distinction and the corresponding denominations (“basic procedure” and “resistance curve procedure”) until today. Up until the 2001 version, E1820 did not require correcting J-integral values for the basic (multi-specimen) procedure to account for crack growth. In 2005, Annex A16 was added for obtaining crack growth corrected J-integral values, and in 2018 the corrections were directly implemented in the J calculation formulae of Annexes A1, A2, and A3. It’s therefore now possible to use to multi-specimen or single-specimen data to establish both critical fracture toughness values and crack resistance curves, and the term “resistance curve procedure” to indicate a single-specimen technique should be considered inaccurate and misleading. In the current ballot, it’s proposed to reinstate the original E813 terminology by replacing “basic procedure” with “multi specimen procedure”, and “resistance curve procedure” with “single-specimen procedure”. In a few instances, “resistance curve procedure” is actually meant to indicate the elastic compliance technique, rather than a generic single-specimen method. All the required modifications are indicated below using the “Track Changes” tool. PLEASE NOTE: this ballot does not include Annexes A8-A11, as these are currently the subject of a different ballot, aimed at (1) allowing multi-specimen crack resistance curves, as well as (2) consolidating procedures for establishing critical values and R-curves for J and ? in two Annexes (A8 and A10) instead of four.