Journal Published Online: 01 November 1990
Volume 18, Issue 6

A Quality Control Test for Selecting Materials to Arrest Fast-Running, Full-Thickness Cracks



A method for measuring full-thickness crack arrest fracture toughness, Ka, using crack-line wedge-loaded compact specimens is described. The unique feature of the test is that so long as the prescribed test method is followed, the data can be analyzed by a small-scale plasticity procedure, with all validity requirements being met. This simple test and analysis procedure, and the fact that every test gives useful data, makes the method suitable for quality control/quality assurance testing.

The test consists of pre-selecting a value of Ka that must be measured, identified as Kv. The specimen size and allowable limits on mouth opening displacement are selected by using Kv and the material's yield strength. The test is then conducted by driving a wedge into the specimen to develop a run-arrest event, after which the specimen is broken open and the crack length at arrest, af, is measured. If af is between 0.4W and 0.8W, Ka is calculable; if the crack length at arrest 0.5W or 0.8W, Ka Kv or Ka Kv.

Crack propagation in the plates on which the test is expected to be used occurs by tunneling. Hence Ka increases with crack extension, attaining its saturation value when the crack attains its equilibrium shape. Measuring saturation values is not needed for quality control/quality assurance testing, however. This allows the use of smaller specimens, but a K-resistance versus crack extension curve for the type of steel being tested is needed to set acceptance criteria.

Author Information

Crosley, PB
Materials Research Laboratory, Inc., Glenwood, IL
Ripling, EJ
Materials Research Laboratory, Inc., Glenwood, IL
Pages: 5
Price: $25.00
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Stock #: JTE12507J
ISSN: 0090-3973
DOI: 10.1520/JTE12507J