Evaluation of plastic eta factors in weld metal fracture specimens: A comparison between limit load and common format solutions
✍ Scribed by J. Donoso; F. Labbé; C. Mora
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 571 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
Abatrati-The values of the plastic eta factor (q,,,) for deeply cracked compact fracture specimens of ASTM AS88 steel, base metal and weld metal were experimentally determined by using limit load solutions and the property of load separation of the corresponding calibration function for the C(T) specimen. The approach taken here is based on the GE-EPRI Handbook's general description of the deformation behavior of the most commonly employed specimen configurations for the experimental evaluation of the fracture toughness of materials, which has led to the concept of the common format equation (CFE) for the calibration functions recently proposed by Landes and Donoso. The method presently employed makes use of the dependence of the limit load, as well as the dependence of the load at various plastic displacements, on normalized ligament size, b/W. The value of q,,, is therefore calculated as the slope of a log-log plot of load, P, versus b/W, at constant plastic displacement. The experimental results obtained with this approach are in good agreement with the values of qti derived from the CFE, as well as with those obtained by using the existing classical relationships for q,,,. In the present case of the C(T) specimens tested, qfi appears to be slightly dependent on the material, and weakly dependent on the value of plastic displacement, but otherwise is independent of crack length. This latter result confirms the convenience of defining a constant, unique value of v~, for each deeply-cracked test specimen configuration, as proposed in the common format equation concept for developing calibration curves for fracture test specimens.