Determination of Threshold Stress Intensity Factors for 7175-T651 Aluminum and Alcoa MA-87 Powdered Aluminum Alloys.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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Threshold stress intensity factors were obtained for two aluminum alloys 7175-T651 and Alcoa MA-87, a powdered alloy. Crack growth tests were conducted at room temperature on a Sonntag Universal fatigue testing machine. Edge-cracked bend specimens were used in the tests. Crack length was checked periodically using a Gaertner cathetometer coupled with an auxillary lens placed close to the specimen. Tests were performed at stress ratios of R 0.1 and R 0.3. It was found that 7175-T651 had a greater fatigue threshold value than MA-87 when compared at the same stress ratio. It was also found that stress ratio had an effect on the threshold stress intensity factors with increasing stress ratio resulting in a smaller fatigue threshold value. Recommendations have been made for further experimentation with regard to threshold stress intensity factors of powdered aluminum alloys. Author
- Metallurgy and Metallography