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was first published in 1996, two ASTM standards existed for elastic-plastic fracture toughness testing: ASTM E813 (withdrawn in 1997), which covered the determination of critical fracture toughness values (JIc, ?Ic), and ASTM E1152 (withdrawn in 1997), which addressed the establishment of J-R crack resistance curves. Another standard, ASTM E1737, which merged E813 and E1152, was published in 1996 and only survived a couple of years, before being withdrawn in 1998 and being replaced by ASTM E1820. ASTM 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, ASTM 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. Since then, the term “basic procedure” has become the generic label for the determination of single-point fracture toughness values, such as Jc and Ju. The distinction between “basic procedure” and “resistance curve procedure” has survived until today. Up until the 2001 version, E1820 did not require correcting J-integral values for the basic procedure to account for the effect of 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 is therefore now possible to use multi-specimen data, calculated according to the basic procedure, to establish both critical fracture toughness values and crack resistance curves. The term “resistance curve procedure”, on the other hand, is only used when the elastic compliance single-specimen technique is intended. In the current ballot, it’s proposed to replace the terminology “resistance curve procedure” with “elastic compliance procedure”. Note that other single-specimen techniques, such as the Electric Potential Difference method (Annex A18) or the Normalization Data Reduction technique (Annex A15) use J calculation formulae that correspond to the Basic Procedure. In a few cases, however, “resistance curve procedure” should be replaced by “single-specimen procedure”. The proposed 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.