Substructural Development During Strain Cycling of Alpha Iron.
WATERLOO UNIV (ONTARIO) DEPT OF CIVIL ENGINEERING
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Substructural developments during reversed axial strain cycling of alpha iron have been studies at room temperature. The nature of the structure varied considerably at different stages of fatigue life. A distinct cell structure developed gradually with continued cycling and the average cell size decreased with increase in applied strain range. A large number of dislocation loops were observed near the regions of the cell walls and their density was higher in specimens cycled at a smaller strain range. Two step tests in which the specimens were cycled at an initial high strain range for a specified number of cycles followed by low strain range cycling showed that although the flow stress decreased rapidly the modification in the substructure was very slow. It is believed that although cross slip is responsible for the substructural development during room temperature fatigue, it is aided by dislocation climb. Author
- Metallurgy and Metallography