Work Item
ASTM WK88032
Revision of E1820-23b Standard Test Method for Measurement of Fracture Toughness
Rationale
An apparent inconsistency regarding the proportions of alternative specimens between sections 7.3, A1.1.2, A2.1.2, and A3.1.2 of E1820-23b was identified. Namely:
• Section 7.3 mentions suggested alternative proportions as 1 <= W/B <= 4 for SE(B) specimens and 2 <= W/B <= 4 for C(T) and DC(T) specimens, adding that “any thickness can be used as long as the qualification requirements are met.”
• Sections A1.1.2 (single edge bend specimens), A2.1.2 (compact specimens), and A3.1.2 (disk-shaped compact tension specimens) only mention the suggested ratios above for alternative specimens, thereby implying they are the only allowed ranges.
This item was already balloted twice, receiving various negatives. Following discussions during the E08.07.05 task group meetings in Denver (May 2023) and Washington DC (November 2023), it was deliberated that, based on available scientific knowledge, W/B ratios much larger than 4 are needed for cracks to transition from flat to slant fracture. Therefore, although the recommended ranges are 1 <= W/B <= 4 for SE(B) specimens and 2 <= W/B <= 4 for C(T) and DC(T) specimens, larger W/B may be used provided it does not lead to slant fracture and/or specimen buckling. This will be indicated consistently in sections 7.3, A1.1.2, A2.1.2, and A3.1.2. Participants in the ASTM discussions also concurred that no knowledge or experience is currently available for low W/B ratios (less than 1 for SE(B) and less than 2 for C(T) or DC(T)), so those lower limits will still be enforced.
Changes with respect to the current E1820-23b language are indicated using “Track Changes” below.
Work Item Status
Date Initiated: 10-02-2023
Technical Contact: Enrico Lucon
Item: 000
Ballot:
Status: