DYNAMIC TEAR ENERGY - A PRACTICAL PERFORMANCE CRITERION FOR FRACTURE RESISTANCE.
NAVAL RESEARCH LAB WASHINGTON D C
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The Dynamic Tear DT method of testing for fracture toughness was developed to overcome the limitations of the Charpy V C sub v test and to provide information of engineering design significance. Key features of the DT test are described, including specimen design, impact test machines, and methods of energy measurement. A relationship exists between the DT energy and the fracture mechanics stress-intensity factor K sub Ic which allows the translation of these energy values into design parameters, such as critical flaw size and stress level, by means of suitable charts. The current need for the use of the DT test in the development and selection of high-strength structural metals has become evident through examples of conditions to which the C sub v test has been shown to be inadequate. For example, when fracture toughness criteria defined by the C sub v and DT tests are compared for a high-strength titanium alloy, a 180-ksi yield strength steel, a 140-ksi yield strength steel weld metal, and a Q and T 2-14 Cr - 1 Mo steel of 90-ksi yield strength, the C sub v test is shown to provide information in variance to that from the DT, DWT-NDT, and Robertson tests. Therefore, it is concluded that the DT test method has desirable features for general industrial use which provide broad-scope characterization of the fracture resistance of steels, titanium alloys, and aluminum alloys. Author
- Metallurgy and Metallography
- Test Facilities, Equipment and Methods