Microstructural approach to fatigue crack processes in polycrystalline BCC materials. Annual technical progress report III
The objectives of the present program are to understand the roles of alloy additions, grain size and yield strength on fatigue threshold and near-threshold growth rates for selected BCC alloys. To accomplish this objective, the full range of single crystal, bi-crystal and polycrystalline materials requires study. These are essential to determine cyclic slip and cyclic cleavage growth rates in the absence of geometrical constraint. Thus far, models of burst cleavage, cyclic cleavage, cleavage fractions, cyclic strain-hardening at low temperatures and mixed microstructural mode growth laws have been derived and partially verified. Experimentally, grain size and low temperatures effects on thresholds and crack growth of HSLA steels and Ti-30 have been completed. Similar studies of Fe-binary alloys are in progress. Single crystal studies are presently underway and electron channelling methods have been developed and calibrated for growth plane and strain distribution analysis.
- Research Organization:
- Minnesota Univ., Minneapolis (USA). Dept. of Chemical Engineering and Materials Science
- DOE Contract Number:
- AS02-79ER10433
- OSTI ID:
- 5557708
- Report Number(s):
- DOE/ER/10433-3; ON: DE82011956
- Country of Publication:
- United States
- Language:
- English
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