Crack Growth Processes at Elevated Temperatures in Advanced Materials
Abstract
Crack tip micromechanics measurements were made the mechanisms of fatigue crack growth were investigated by direct observation of crack growth using a cyclic stage in the scanning electron microscope. Direct measurements of fatigue crack closure were made for center notched specimens of the aluminum alloy 7091, and these were compared to similar measurements from single edge notched specimens of the same alloy. The results indicate that plasticity induced closure can be treated in a systematic way and is linked to the threshold for fatigue crack growth. A simple model was developed which can be used to simulate the opening of fatigue cracks. These results were then compared to similar information from stainless steel, aluminum, and titanium alloys. Some general conclusions about closure were identified. The roles of microstructure in the fracture toughness and tensile ductility of the two-phase Ti3Al-base and TiAl base alloys were established by identifying the relevent fracture and toughness processes in these alloys by performing crack-tip micromechanics experiments both at ambient and elevated temperatures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA233574
Entities
People
- David L. Davidson
- James Lankford
- Kwai S. Chan
Organizations
- Southwest Research Institute