Corrosion fatigue of small cracks: Mechanics and chemistry: Final technical progress report, July 1, 1984-October 31, 1987

Technical Report · Mon Mar 07 00:00:00 EST 1988

OSTI ID:5029847

Wei, R P

The principal contributions of this study have been briefly summarized. Firstly, electrochemical reaction control of corrosion fatigue crack growth in ferrous alloys was demonstrated. The controlling reactions are those involving equilibration of the crack-tip bare surfaces with its neighboring filmed or oxidized surfaces. Secondly, the electrolyte within the crack serves as a high resistance path that separates the crack tip region from the bulk (external) environment. Because of this high resistance, the crack tip region is effectively shielded and the reactions are affected little by the externally imposed conditions, with the crack-tip potential tending to remain very near the free corrosion potential. Thirdly, with increases in test temperature, it becomes increasingly difficult to displace the crack-tip potential away from the free corrosion potential. In other words, because of the increased reaction rate at higher temperatures, larger currents must be imposed to maintain the surface at a prescribed potential. The increased currents, however, result in greater potential drop along the crack, and thereby reduces the change in potential at the crack tip under a fixed applied potential. The details of electrochemical conditions and of the mechanisms of reactions, however, are much more complex, and would require further study. Fourthly, the results provide further support for hydrogen embrittlement as the mechanism for crack growth enhancement for the austenitic stainless and the carbon strengthened steels. Lastly, the role of grain boundaries in influencing short-crack growth response has be elucidated.

• Research Organization: Lehigh Univ., Bethlehem, PA (USA). Dept. of Mechanical Engineering and Mechanics
• DOE Contract Number: FG02-84ER45138
• OSTI ID: 5029847
• Report Number(s): DOE/ER/45138-T2; ON: DE88007955
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CORROSION FATIGUE
CRACK PROPAGATION
STAINLESS STEEL-304
FATIGUE
STEELS
CRACKS
AUSTENITIC STEELS
ELECTROCHEMISTRY
HYDROGEN EMBRITTLEMENT
KINETICS
PROGRESS REPORT
ALLOYS
CHEMISTRY
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
DOCUMENT TYPES
EMBRITTLEMENT
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MECHANICAL PROPERTIES
NICKEL ALLOYS
STAINLESS STEELS
360103* - Metals & Alloys- Mechanical Properties