Evaluation of KISCC and da/dt Measurements for Aluminum Alloys Using Precracked Specimens / MS. Domack
- Conference Author:
- Environmentally Assisted Cracking: Science and Engineering (1987 : Bal Harbour, Florida)
- Physical Description:
- 1 online resource (17 pages) : illustrations, figures, tables
- Additional Creators:
- Domack, MS.
American Society for Testing and Materials
- Restrictions on Access:
- License restrictions may limit access.
Subscription required for access to full text.
- The results of an interlaboratory program conducted to evaluate variability in measurements of the threshold stress intensity factor (KISCC) and stress corrosion crack growth rates (da/dt) for aluminum alloys are summarized. Precracked specimens machined from 7075-T6 aluminum alloy plate are exposed to a 3.5% NaCl (sodium chloride) solution by eleven participating laboratories. The effects of specimen configuration, starting stress intensity level, precracking procedure, and surface grooving are statistically evaluated, and sources of both interlaboratory and intralaboratory variability are identified. Data analysis indicates that variations in crack growth rates were related to difficulties associated with visual crack length measurements, especially on face-grooved specimens, and that more effective measurement techniques would more accurately characterize stress corrosion crack growth. In addition, test duration should be determined systematically, accounting for crack length measurement resolution, time for crack arrest, and experimental interferences. Variations in KISCC were related to the procedure used to measure the final bolt load. Final load measured by specimen reloading did not correlate well with that determined by compliance and appeared sensitive to factors such as corrosion product wedging and metallurgical features on the stress corrosion crack faces. Miniature instrumented load cells were used in several tests in a parallel program to monitor load relaxation during specimen exposure and to provide an indication of final load prior to specimen reloading. The load cell output during specimen exposure indicated that perturbations observed in crack length versus time curves may be related to real changes in load and should not be considered due only to crack length measurement difficulties. Compliance solutions were experimentally determined for both modified compact and double-beam wedge loaded specimens with different face-groove geometries and the results compared with published solutions. Both crack-mouth and load-line crack opening displacements were measured, and the data were used to define a relationship to correlate deflections at these measurement locations. The resulting relationship is compared with a previous solution determined by boundary collocation. No significant statistical variation in KISCC was observed with regard to specimen type, surface grooves, or specimen orientation, indicating both specimen configurations are suitable for stress corrosion testing and differences in KISCC determination were attributed to test procedures. Results of both the interlaboratory program and the additional studies should provide important contributions toward the development of a standard test method for stress corrosion testing and analysis using precracked specimens.
- Dates of Publication and/or Sequential Designation:
- Volume 1990, Issue 1049 (January 1990)
- Alloys—Fracture—Environmental aspects—Congresses
- Aluminum alloys
- Double-beam bolt-loaded specimen
- Environmental engineering
- Fatigue (materials)
- Fracture mechanics
- Metals—Fracture—Environmental aspects—Congresses
- Metals—Cracking—Environmental aspects—Congresses
- Modified compact bolt-loaded specimen
- Precracked specimens
- Stress corrosion
- Digital File Characteristics:
- text file PDF
- Bibliography Note:
- Includes bibliographical references 16.
- Other Forms:
- Also available in PDF edition.
Also available online via the World Wide Web. Tables of contents and abstracts freely available; full-text articles available by subscription.
Full text article also available for purchase.
- Reproduction Note:
- Electronic reproduction. W. Conshohocken, Pa. : ASTM International, 1990. Mode of access: World Wide Web. System requirements: Web browser. Access may be restricted to users at subscribing institutions.
- Technical Details:
- Mode of access: World Wide Web.
- Source of Acquisition:
- ASTM International PDF Purchase price USD25.
View MARC record | catkey: 27996215