Evaluation of the single edge notch tension specimen for quantifying fracture toughness – Participation in a round-robin test program

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Authors
  1. Bayley, C.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN)
Abstract
DRDC was asked to participate in a round-robin program investigating a new test protocol to measure the fracture toughness of steels and welds. The round-robin program utilized a testing procedure being examined by the Pipeline Research Council International using a single edge notch tension (SENT) specimen, rather than the more conventional single edge bend specimen. Twelve SENT specimens were tested in a 500 kN test frame at room temperature with notches located in either the base metal, fusion line or weld centerline. Periodic unloading compliance measurements were programmed into a customized control routine in order to estimate the crack length throughout the test duration. At each unloading point, the crack tip opening displacement (CTOD) was determined by either a geometrically based Double Clip Gauge (DCG) procedure, or computed from the elastic plastic fracture toughness parameter J. Tearing resistance curves were computed, with significant discrepancies noted between the two different fracture toughness measurement approaches. The most striking difference was associated with the fusion line specimens, and was attributed to invalid material constants. Since the DCG approach does not require an assumption of the mechanical properties of the given material, it is likely a better approach for heterogeneous materials or when the notch is located within a graded microstructure.

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Keywords
fracture mechanics;steel
Report Number
DRDC-RDDC-2015-R156 — Scientific Report
Date of publication
01 Aug 2015
Number of Pages
72
DSTKIM No
CA040798
CANDIS No
802059
Format(s):
Electronic Document(PDF)

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